The Science & Practice of Perfecting Your Sleep | Dr. Matt Walker

welcome to the hubermann lab podcast where we discuss science and science-based tools for everyday life i'm andrew huberman and i'm a professor of neurobiology and ophthalmology at stanford school of medicine today i have the pleasure of introducing dr matthew walker as our guest on the huberman lab podcast dr walker is a professor of neuroscience and psychology at the university of california berkeley there his laboratory studies sleep they study why we sleep what occurs during sleep such as dreams and why we dream learning during sleep as well as the consequences of getting insufficient or poor quality sleep on waking states dr walker is also the author of the international bestselling book why we sleep our discussion today is an absolutely fascinating one for anyone that's interested in sleep learning or human performance of any kind dr walker teaches us how to get better at sleeping he also discusses naps whether or not we should or should not nap whether or not we can compensate for lost sleep and if so how to best do that we discuss behavioral protocols and interactions with light temperature supplementation food exercise sex all the variables that can impact this incredible state of mind and body that we call sleep during my scientific career i've read many papers about sleep and attended many seminars about sleep yet my discussion with dr walker today revealed to me more about sleep sleep science and how to get better at sleeping than all of those papers and seminars combined i'm also delighted to share that dr walker started a podcast that podcast entitled the matt walker podcast releases its first episode this month and is going to teach all about sleep and how to get better at sleeping so be sure to check out the matt walker podcast on apple spotify or wherever you listen to podcasts before we begin i'd like to mention that this podcast is separate from my teaching and research roles at stanford it is however part of my desire and effort to bring zero cost to consumer information about science and science related tools to the general public in keeping with that theme i'd like to thank the sponsors of today's podcast our first sponsor is roca roca makes sunglasses and eyeglasses that are of the absolutely highest quality the company was founded by two all-american swimmers from stanford and everything about the design of their glasses is with performance in mind i've spent my career studying the visual system and how it works i can tell you that roka glasses take into account the science of the visual system such that whether or not you're wearing them on a very bright day or you walk into a shadowed area or there's cloud cover you can still see everything with perfect clarity that also reflects the fact that the lenses that they use are of the absolute highest optical quality the other terrific thing about roca sunglasses and eyeglasses is that they're designed to be worn in all conditions you can use them while running while 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code huberman by going to belcampo.com huberman and if you do that you'll get 20 off your first order i'm a big fan of their keto meatballs i also really like their boneless rib eyes i eat those pretty much once a day again that's huberman for the code and it's balcampo.com huberman for 20 off your order and now my discussion with dr matt walker great to finally meet you in person wonderful to connect um i mean it's been too long but i suspect it would have been a shorter time before we'd met lest the pandemic yeah um thank you thank you yeah i'm delighted that we're finally sitting down face to face i've been tracking your work both in the internet sphere and i read your book and loved it and also from the perspective of science you actually came to stanford a couple of years ago and gave a a lecture uh for brain mind oh yeah yeah yeah yeah and um there of course uh you talked about sleep and its utility and its challenges and how to uh and how to conquer it so to speak um let's start off very basic what is sleep sleep is probably the single most effective thing you can do to reset your brain and body health so that's a functional answer in terms of you know what is sleep in terms of its benefits sleep as a process though is an incredibly complex physiological ballet and if you were to recognize or see what happens to your brain and your body at night during sleep you would be blown away and the paradox is that most of us and i would think this too you know if i wasn't a sleep scientist we go to bed we lose consciousness for seven to nine hours and then we sort of wake up in the morning and we generally feel better and in some ways that denies the physiological and biological beauty of sleep so upstairs in your brain when you're going through these different stages of sleep the the changes in brainwave activity are far more dramatic than those that we see when we're awake and we can speak about deep sleep and what happens there rem sleep is a fascinating time which is another stage of sleep often called dream sleep which is rapid eye movement sleep that stage of sleep some parts of your brain are up to 30 percent more active than when you're awake so again it's kind of violating this idea that our mind is dormant and our body is just simply quiescent and and resting so i would happy to sort of double click on either one of those and also what changes in the body as well but it is an intense evolutionary adaptive benefit um and system that said though i i would almost push back against uh an evolved system when we think about the question of sleep and what sleep is our assumption has always been that we evolved to sleep and i've actually questioned that and i have no way to get in a time capsule and go back and prove this but what if we started off sleeping and it was from sleep that wakefulness emerged why do we assume that it's the other way around and i think there's probably some really good evidence that sleep may have been the proto state that it was the basic fundamental living state and when we became awake as it were we always had to return to sleep you know in some ways at that point sleep was the price that we paid for wakefulness and that's another way of describing what sleep is but again i think it sort of denies that the active state of sleep it's not a passive state of sleep either and then finally you can say what what is sleep across different species and in us human beings and in all mammalian species and avian species as well sleep is broadly separated into these two main types and we've got non-rapid eye movement sleep on the one hand and then we've got rapid eye movement sleep on the other and we can speak about how they unfold across a night and their architecture because it's not just intellectually interesting from the perspective of what sleep is it's also practically impactful for our daily lives and i'd love to sort of go down that route too but you navigate you tell me i can let's definitely go down that route so um you mentioned how active the brain is during certain phases of sleep when i was coming up in science rem sleep rapid eye movement sleep was referred to as paradoxical sleep is that still a good way to think about it paradoxical because the brain is so active and yet we are essentially paralyzed correct yeah it really is a paradox and where that came from was simply the brainwave recordings that if all i'm measuring about you is your brainwave activity it's very difficult for me sitting outside of the sleep laboratory room to figure out are you awake or are you in rem sleep because those two patterns of brain activity are so close to one another you can't discriminate between them yet the paradox is that when you are awake i go in there and you're sort of sitting up you're clearly conscious and awake but yet when you go into rem sleep you are completely paralyzed and that's one of the i think that's part of the paradox but the paradox really just comes down to two dramatically different conscious states yet brain activity is dramatically more similar than different and the way i can figure out which of the two you are in is by measuring two other signals the activity from your eyes and the activity from your muscles so when we're awake we will occasionally have these blinks and we'll have sort of circads but during rem sleep you have these really bizarre horizontal shuttling eye movements that occur and that's where the name comes from rapid eye movements are they always horizontal mostly they are horizontal and that's one of the ways that we can differentiate them from other waking eye movement activity because it's not always like it can be sometimes horizontal but can also have diagonal and also vertical in that plane but then the muscle activity is the real dead giveaway just before you enter rem sleep your brain stem which is where the dynamics of non-rem and rem are essentially played out and then expressed upstairs in the cortex and downstairs in the body when we go into rem sleep and just a few seconds before that happens the brain stem sends a signal all the way down the spinal cord and it communicates with what are called the alpha motor neurons in the spinal cord which control the voluntary skeletal muscles and it's a signal of paralysis and when you go into dream sleep you are locked into a physical incarceration of your own body amazing you know why why would mother nature do such a thing and it's in some ways very simple the brain paralyzes the body so that the mind can dream safely because think about how quickly we would have all been popped out of the gene pool you know if i think i'm you know one of the best skydivers who can just simply fly and i've had sometimes those dreams too you know and i get up on my apartment window and i leap out you're done you're done yeah you know so that's one of the sort of that's part of the paradox of rem sleep both its brain activity similarity despite the behavioral state being so different and this bizarre lockdown of the sort of brain of the body itself now of course the involuntary muscles thankfully aren't um paralyzed so you keep breathing your heart keeps beating is this why men have erections during rem sleep and women have vaginal lubrication during sleep that's one of the reasons part of the other reason though though is because of the autonomic activity so there is a nervous a part of our nervous system called the autonomic nervous system and it controls many of the automatic behaviors and some of those are aspects of our reproductive facilities during rem sleep what we later discovered is that you go through these bizarre what we call autonomic storms which sounds dramatic but it actually is when you measure them that you'll go through periods where your heart rate decelerates and drops and your blood pressure goes down and then utterly randomly your heart rate accelerates dramatically and what we call the fight or flight branch of the autonomic nervous system or the sympathetic nervous system badly named because it's anything but sympathetic it's very aggravating and that all of a sudden fires up and then it shuts down again and it's not in any regular way and it's when you get those autonomic storms you get very activated from a physiological perspective that you can have these erections and you have vaginal discharge etcetera you're totally paralyzed but you are still paralyzed there are only um two voluntary school two voluntary muscle groups that are spurred from the paralysis bizarre one your extraocular muscles because if they were paralyzed you wouldn't be able to have rapid eye movements and the other that we later discovered was the inner ear muscle and we've got no good understanding as to why those two muscle groups are spurred from the paralysis it may have something to do with cranial nerve but i i don't think it's that i think it's perhaps something more sensory related some people have argued that the reason the eyeballs are spurred from the paralysis is because if your eyeballs are left for long periods of time inactive you may get things such as oxygen sort of issues in the um aqueous or vitreous humor and so the eyeballs have to keep the drainage systems of the anterior eye are made to require movement exactly people with glaucoma have deficits in in drainage through the anterior chamber but there i'm speculating i'm also speculating when i ask this um i would imagine that there are states in waking that also resembles slow wave sleep or rather that there are states that slow wave sleep also resembles waking states you've beautifully illustrated how rem sleep can mimic some of the more active brain states that we achieve in waking what sort of waking state that i might have experienced or experience on a daily basis might look similar to slow wave sleep non-rem sleep if any it's a genius way of thinking about it turns the tables i love it um we almost never see anything like the the true ultra slow waves of deep non-rem sleep so um we spoke about these two stages non-rem and rem um non-rem is further subdivided into four separate stages um stages one through four increasing in their depth of sleep so stages three and four that's what we typically call deep non-rem sleep stages one and two so maybe take me through the arc of a night just so that yeah yeah so i put my head down uh well for you what time do you normally go to sleep so i'm usually sort of around about a 10 30 p.m guy and usually i'll naturally wake up sort of a little bit before seven sometimes before 6 45 or 7. i have an alarm set for um 704 um a.m you heard it here folks matt walker does use an alarm clock i really really i'm usually he doesn't recommend it but he does use it yeah i usually human after all oh i am so human um and and i've had my sleep issues and i'd love to speak about that too but um it's only just you know in the event that um you know because i like to keep regularity too you've got to keep those two things in balance and 704 just because you know why not be idiosyncratic i don't know why we always set things up on these uh hard numbers so yep so when you go to sleep around 10 30. so using you as an example um because i imagine a number of people go to sleep at different times with 10 30 is about when i go see 11 is for me but um so you go to sleep at 10 30. so for that first um let's say three hours of sleep what is the architecture of that sleep look like as compared to the last three hours of your sleep uh before morning yeah so i should note that that sort of you know 10 30 to 7 that's just based on my chronotype and my preferential it's different for different people i'm not suggesting that that's the perfect sweet spot for humanity's sleep it's just my but i imagine most people probably go to sleep somewhere between ten and p.m and midnight and most probably like five a.m and seven a.m or 5 30 and 7 30. yeah yeah um at least in if you look at sort of first world nations that's that's a typical sleep profile um so when i first fall asleep i'll go into the light stages of norm sleep stages one and two of non-rem and then i'll start to descend down into the deeper stages of non-rem sleep so after about maybe 20 minutes i'm starting to head down into stage three non-rem and then into stage four non-rem sleep and as i'm starting to fall asleep as i've cast off from the usually with me murky waters of wakefulness and i'm in the shallows of sleep stages one and two my heart rate starts to drop a little bit and then my brainwave pattern activity starts to slow down normally when i'm awake it's going up and down maybe 20 30 40 50 times a second as i'm going into light non-rem sleep it will slow down to maybe 15 20 and then really starts to slow down down to about sort of ten or eight cycles per second eight cycle waves per second then as i'm starting to move into stages three and four non-rem sleep several remarkable things happen all of a sudden my heart rate really does start to drop oh and i'll come back to temperature i'm going to write temperature down because i always forget these things um now i'm sadly in the foothills of middle age so as i'm starting to go into those deeper stages of non-rem sleep all of a sudden hundreds of thousands of cells in my cortex all decide to fire together and then they all go silent together and it's this remarkable physiological coordination of the likes that we just don't see at during any other brain state that's really interesting having recorded from the brains of animals and a little bit from humans i don't think i've ever seen the entire cortex or even entire regions of cortex light up like that yeah it's it's stunning it's it's almost like this beautiful sort of mantra chant um or this sort of you know it's a slow inhale and then a meditative exhale inhale exhale and these waves are just enormous in their size and the body is capable of movement at this time there is no paralysis there is no paralysis but for the most part muscle tone has also dropped significantly interesting at that point and then you will or i will then stay there for about another 20 or 30 minutes so now i'm maybe 60 or 70 minutes into my first sleep cycle and then i'll start to rise back up back up into stage 2 non-rem sleep and then after about 80 or so minutes i'll pop up and i'll have a short rem sleep period and then back down i go again down into non-rem up into rem and you do that reliably repeatedly and i will be doing that and i do do that every 90 minutes at least that's the average for most adults it's different in different species what changes to your question is the ratio of non-rem to rem within that 90-minute cycle as you move across the night and what i mean by this is in the first half of the night the majority of those 90-minute cycles are comprised of lots of deep non-rem sleep that's when i get my stage three and four of deep non-rem sleep once i push through to the second half of the night now that seesaw balance changes and instead the majority of those 90-minute cycles are comprised either of this lighter form of non-rem sleep stage 2 non-rem sleep and much more an increasingly more rapid eye movement sleep and the implication that i was sort of speaking about pragmatically is let's say that um i have to and i usually never do early morning flights or red eyes um just because i'm a mess if that happens i'm not suggesting that other people shouldn't i'm suggesting just will not do that every time i've taken a red eye or i've done that two or three days later i get some sort of general feeling of malaise my brain doesn't work as well i i think red eyes should be abolished i for the pilots too i mean and we can forget about those and for the emergency room i mean long shifts have been shown to lead to you know physician-induced uh errors that uh lead to a lot of fatalities i mean there are a lot of reasons why staying up too long or being up at the wrong times if you're not adapted to is just terrible the data in all of those cases you know and particularly physicians too there was some recent data looking at suicidality and the rates of suicide in training physicians are you know far far above the norm and i don't suspect that you know their schedules are helping them i suspect that sleep is a missing part of that explanatory equation but i teach medical students and and they they're phenomenal but yeah they're under extremely challenged conditions it's uh we shouldn't put them under no it's not it's not optimizing performance um i'm sorry i'm sorry no no this is important these um it's an important digression i have one question which is you're saying that as across the night a greater percentage of these 90-minute cycles are going to be occupied by rem sleep as you progress through the night i'm aware that they're based on work that you've done and uh and from your public education efforts and others um that we have so-called circadian forces and we have other forces that are driving when we sleep and when we want to sleep et cetera without going into the details of those have a simple question the experiment is the following let's say god forbid you are prevented from going to sleep at your normal time and you stay up for the four hours or five hours that normally you would be in predominantly slow wave sleep yep if let's say you finally get to lie down at 3 am a time when normally your sleep would be occupied mostly by rapid eye movement sleep will you experience a greater percentage of rapid eye movement sleep because of these so-called circadian forces meaning that's what's appropriate for that time or will your system need to start at the beginning of the race that were as as i'm referring to it that we're calling sleep yeah and for if that's not clear to anybody basically what i'm asking is if you are forced to skip the slow wave sleep part of the night will your system leap into rapid eye movement sleep or does it have to start at the beginning and get slow wave sleep first in other words does one sleep state drive the entry to the next sleep state great question so there is some degree of reciprocity between the sleep states i should note that when we drive one of those up we often but not always see a change in the other there are some pharmacologies that have shown an independence to that and we've also played around with things like temperature and sometimes you can you know nudge one and not seem to upset or perturb the other but to your um i think lovely point the answer is it's a mix but it's mostly the latter meaning you will mostly go into your rem sleep phases and be significantly deficient in your deep sleep so just because i start my sleep cycle at 3 00 am rather than at 10 30 pm it doesn't mean that my brain just says well i've got a program and i'm just going to run the program and the way the program runs is that we always start with a first couple of hours of deep sleep so we're just gonna begin act number one scene one it doesn't do that now i will get some deep sleep to begin with and part of that is just because of how sleep works based on how long i've been awake longer i'm awake there is a significantly greater pressure for deep sleep but we actually use exactly what you just described as an experimental technique to selectively deprive people of one of those stages of sleep or the other so we will do first half of the night deprivation and then let you sleep the second half so that means that you will be mostly deep sleep deprived and you will still get mostly all of your rem sleep and then we switch it so you only get your first four hours which means you will mostly get deep non-rem sleep but you will get almost no rem sleep so in both of those groups they've both had four hours of sleep so the difference between them in terms of an experimental outcome is not the sleep time because they've both slept for the same amount it's the contribution of those different stages now we actually have more elegant methods for sort of selectively going in there and scooping out different stages of sleep but that's the way we used to do it old school was just using this timing difference and who suffers more those that lack the early phase and where those that lack the later phase of the night sleep in other words if i have to sleep only four hours for whatever reason am i better off getting the early part of the night's sleep or the second half of the night's sleep depends on what the outcome measure is um so that gets right to the differences between slow wave sleep and rem right i was um probably misinformed but my understanding a very crude understanding i should i should say before i very much doubt it's no contra with someone like you yeah which is that they're very nice of you but the the first part of the night the slow wave sleep is restorative to the musculature to motor learning and that the dream content tends to be less emotional the second half of the night being more emotional dreams and sort of the unpairing of the emotional load of our previous day and other experiences so in other words if i were to deprive myself deprive myself excuse me of rem i would be hyper-emotional not maybe not as settled with the kind of experiences of my life whereas if i had to have myself of slow wave sleep i would feel a more physical malaise is that correct or is that far too simple and if it is too simple please uh tell me where i'm wrong no i think much of that is correct and it's sort of that plus so for example during deep non-rem sleep that's where we get this it's almost a form of natural blood pressure medication and so when i take that away from you the next day we're usually going to see autonomic dysfunction we're usually going to see abnormalities in heart rate blood pressure we also know that during deep non-rem sleep that there is a certain control of specific hormones for example we know that the insulin regulation of sort of metabolism meaning how will you look from a regulated blood sugar perspective versus dysregulated pre-diabetic look of profile that's where deep sleep seems to matter if we selectively deprive you of that we can see them growth hormone is different actually so that's that's a beautiful demonstration where growth hormone seems to be more rem sleep dependent and that's why we can come on to the effects of alcohol and there's some really impressive frightening data on on alcohol in its disruption of um of sleep but then we also know testosterone you know peak levels of testosterone happen during rem sleep so the second half of the night which is the second half of the night so it really just means that the your profile of mental and physical dysfunction will be different under both of those conditions which one would you prefer i would prefer neither of them and it really depends on what you're trying to optimize for so it's it's just so complex you know sleep is just so pluripotent you know it's so physiologically systemic that it's almost impossible not to undergo one of those two things just deep sleep deprivation or just rem sleep deprivation and not show a profile that you would really prefer to avoid uh and that's that that's the reason from an evolutionary standpoint that we've preserved those stages of sleep i mean sleep is just so idiotic you know from an evolutionary perspective or maybe waking is idiotic or waking is you know well yeah i based on your previous yeah who have you been talking to i think that comment is very specific to me um yeah i am normally um always an idiot when waking but i think this this idea that sleep you know is so profoundly detrimental to us if you were to take it at face value you know you're not finding a mate you're not reproducing you're not foraging for food you're not caring for your young and worst of all you're vulnerable to predation on any one of those grounds sleep probably should have been selected against but it wasn't sleep has fought its way through heroically you know every step along the evolutionary path and therefore every sleep stage has also survived as best we can tell what that means is that those are non-negotiable if mother nature had found a way to even just sort of you know thin slice some of that sleep from us there would have been vast i'm sure evolutionary benefits but it looks as though she hasn't and i'm usually in favor of her wisdom after 3.6 million years so um yeah it's incredible i want to introduce a another um gadonkan experiment another thought experiment so in this arc of the night slow wave sleep predominates early in the night and then rem sleep there's a scenario that many people including myself experience on a regular basis which is they go to sleep sleeping just fine three four hours into it they wake up yeah they wake up for whatever reason maybe there's a noise maybe the temperature isn't right we will certainly talk about sleep hygiene etc they get up they go to the restroom they might flip on the lights they might not they'll get back in bed hopefully they're not picking up their phone and starting to browse and wake up the brain through various mechanisms light and cognitive stimulation etc they go back to sleep let's say after about 10-15 minutes they're able to fall back asleep and then they sleep till their more typical wake time yeah how detrimental is that wake-up episode or or um event in terms of longevity learning etc i would love to sleep the entire night through every night but most nights i don't and yet i feel pretty good throughout the day some days better than others so if you were to kind of evaluate that waking episode and compare it to sleeping the whole night through what are your what are your thoughts on that so i think if you're waking up sort of frequently as you're describing i would probably get your estate in order because my guess is within the next year you're going to be you're going to be done for no i'm kidding you absolutely kidding you it is perfectly natural and normal particularly as we progress with age you know children tend to have typically more continuous sleep now it's not that they aren't waking up for brief periods of time they are and in fact we all do when we come out the other end of our sleep cycle at the end of our rem sleep period of the 90-minute cycle almost everybody wakes up and we make a postural movement we turn over because we've been paralyzed for so long and the body will also like to shift do we ever look around we ever open our eyes position you some sometimes people will open their eyes but usually it's only for a brief period of time and they usually never commit those awakenings to memory right your situation and it's my situation as well i usually now at this stage of life i don't sleep through the night i'll usually have a bathroom break and then i'll come back that's perfectly normal we tend to forget that in sleep science we think of sleep efficiency so of the total amount of time that you're in bed how much of that percent time is spent asleep and we usually look to numbers that are above 85 percent or more as a healthy sleep efficiency so if you were to think about me going to bed and i spend you know let's say eight and a quarter eight and a half hours of time in bed with a normal healthy sleep efficiency i still may be only sleeping a total of seven and a half hours or seven and three quarter hours meaning that i'm going to be awake in total not in one long bout but i'm going to be awake for upwards of 30 minutes net some time sometimes that can be after a 10 minute you know dalliance after having gone to the bathroom and i'm just gradually drifting back off again other times it will just be for a couple of minutes and most of those you don't commit so i think we need to stop we don't need to get too worried about you know periods of time awake just because we're not sleeping throughout the night i would love to do that too and i remember when i that used to happen and it still happens occasionally it feels great it's a lovely thing it's a surprise right it is now a surprise for the whole night yeah it is a surprise but for the most part i think we can be more relaxed about that where we have to be a bit more attentive though is if you are spending long periods of time not being able to get back to sleep and usually we define that by saying if it's been 20 25 minutes normally that's a time when we would really say okay let's explore this what's going on let's see what's happening the other thing is if it's happening very frequently so even if you're um you know not awake for 25 minutes stretches but you're finding yourself waking up and being consciously aware that you've woken up for maybe six seven or eight times throughout the night and your sleep is very what we call fragmented the great science of sleep in the past five or ten years has has been yes quantity is important but quality is just as important and you can't have one without the other in terms of a good beneficial next day outcome you can't just get four hours of sleep but brilliant quality of sleep and be unimpaired nor can you get eight hours of sleep but have very poor quality of sleep and be unempowered the next day so that's why i just sort of want to asterisk this idea of let's not get too worried about waking up and having some time awake that's perfectly normal and natural but if it's happening very frequently throughout the night all those periods of time are long stretches of time upwards of 25 minutes then let's look into it well i can assure you just helped a lot of people uh feel better about this waking up episode that i and many other people experience i i hope so because i i because i think it's really important that we you know i think i've been desperately guilty of perhaps you know early on being too puritanical about you know sleep and and and i've i've retrospected and i've tried to explore why this was the case you know it was almost sleep or else dot dot dot you know and at the time when i was starting to write the book which was back in 2016 you know sleep was still a neglected step sister in the health conversation of today and i could have certainly changed and it's changing you know and not because of my efforts but no i always my colleagues i would say well i it's a great um that you give a attribution to your other people involved and of course it's a big field but i think um you've done a great service by cueing people to the importance of this state not just for avoiding troublesome outcomes but also for optimizing their waking state it's real you know i i view sleep as this period that feels good but we're not aware of how it feels when we're in it necessarily yeah um has tremendous benefits when you're doing it well so to speak and it has tremendous um deficits when when we're not and i think i think it was an important thing for you to do to cue people to this issue and i would say mission accomplished that people are aware of the need for sleep i think that knowing that waking up in the middle of the night is normal provided it's not too frequent is is great and will also help people who may have been overly concerned about that i i do want to use this as an opportunity to raise something about the so-called uberman schedule not to be confused with the hubermann um fortunately no one uh has confused those yet um some years ago there was a discussion about the so-called ubermen schedule meaning the superman schedule so that's huberman without an h which i have nothing to do with um if you read your nietzsche this might this will have a subtext but regardless um the uberman schedule as i understand is one in which um the person elects to sleep in 90-minute bouts spread throughout the day and night in an attempt to get more productivity and or reduce their overall sleep need there was a paper published recently that explored whether or not this is good or bad for us maybe you just give us the take-home message on that yeah so these uberman like uh schedules and there's lots of different forms of that they tried to essentially pie chart the 24-hour period into short bouts of sleep with some shorter or no well slightly longer periods of wakefulness then short bouts of sleep then wakefulness you know you're i sort of made it i think a quip it's almost like you're sleeping like a baby you know because that's the way that babies in 90 minutes will sleep they all have you know these brief naps then they're awake then they're asleep in the rake and to the chagrin of parents across the night it's basically the same they're awake they're asleep they're awake they sleep and that's more the the schedule that these types of protocols have have suggested and there was a really great comprehensive review that found not only that they weren't necessarily helpful but they were actually really quite detrimental and on almost every performance metric whether it be task performance whether it be physiological outcome measures whether it even be the quality of the sleep that they were having when they were trying to get it all of those were in a downward direction and it's not surprising if you look at your the way that your physiology is programmed if you look at the way your circadian rhythm is programmed none of that screams to us that we should be sleeping in that way well i'm chuckling because we always hear sleep like a baby this is how babies sleep and uh i would say don't sleep like a baby sleep like an adult yeah i mean get your solid eight hours billy crystal's line he was a um you know a long-standing suffering insomniac he says i sleep like a baby i'm awake every 20 minutes you know and i think this is another one of those demonstrations that when you fight biology you normally lose and the way you know you've lost is disease sickness and impairment and i think if you sleep in accordance with the natural biological edict that we've all been given life tends to be both of a higher quality and a longer duration yeah i agree along those lines um i'm as a vision scientist i've been very excited by the work on these uh non-image forming cells in the eye the so-called melanopsin cells that inform the brain about circadian time of day and i'm a big proponent of people getting uh some sunlight ideally sunlight but other forms of bright light in their eyes early in the day and when they want to be awake essentially during the phase of their 24-hour circadian cycle when temperature is rising and then starting to get less light in their eyes as our temperature is going down in terms of later in the day and in the evening are there any adjustments to that general theme that you'd like to add or is in any way no i think that's exactly what we recommend right now which is try to get at least 30 to 40 minutes of exposure to some kind of natural daylight now there may be parts of the world where you know you're from you're from a rather cloudy part of the world i am from yeah uh liverpool england uh and uh the northwest of england is not known for its um beach resorts and fine weather uh i remember i'd sort of i went back home for a trip when i'd first been out uh in california and i thought why is the sky so low you know it's just you know constantly out we joke that in um in the uk we usually have nine months of bad weather and then three months of winter and then that's your that's your entire year of in terms of a climate but to come to your point you're exactly right try to get that daylight now it can be you know working next to a window and you're getting that natural sunlight but that natural sunlight is even on a cloudy day in england is usually far more potent than anything that you'll get from indoor lighting despite you thinking sort of from a perception-wise maybe they're much closer than i would think yeah i've been um sorry to interrupt i've been a big proponent of there's a an app called light meter which will it's a free app i have nothing to do with it that will allow you to get a pretty decent measurement of the amount of light energy coming toward you and if you um hold it up to a cloudy morning where you don't think it's very bright out kind of a dismal day you'll notice that there'll be a thousand two thousand even you know five thousand looks looks just being a measure of brightness of course and then you can point the same light meter toward an indoor light that seems very bright and very intense and it'll say 500 blocks and you realize that the intensity as we gauge it perceptually is not really what the system is receiving so outdoor light is key how do you how do you get this natural stimulation or um i should just say light stimulation early in the day what is your typical what does matt walker do to get this light stimulation i am no poster child but um usually i will um if i'm working i usually work out most days um and i shopped around and i found a gym that has huge amounts of window exposure facing to the east this is sad this is gonna sound so uh ridiculous you know matt walker chooses a gym on the basis i love it the solar input so he can you know there are a lot of criteria for selecting gyms this one is actually grounded in physiology and biology and so and selfishness about my own sleep that's great so you so you get your exercise and your light stimulation that's right yep yep and so you're stacking cues for wakefulness early in the day exactly so both exercise and daylight are wonderful cues for circadian rhythm alignment and also circadian rhythm reset each day and so i will use both exercise i mean i am i'm neither a strong morning type or a strong evening type and my preference to exercise is probably sometime in the middle of the day probably somewhere around 1 8 1 pm sorry not 1 am um but i'm usually working out probably around the sort of seven sort of 45 8 a.m time that's usually when i'll start my workout and there i'll start with cardio spin bike facing a window and luckily for the most part here in california there's usually sunlight coming through but it doesn't matter to me because just as you said even when it's a cloudy day that looks coming through of light the the intensity is is splendid so i would prefer to favor my exercise just because for efficiency too i want to get also working on the day i'll try to match my exercise more with my circadian light exposure than i would probably if i'm going to do i really want to crush a workout or do i want to just you know make sure it's a good workout i would prefer to work out you know at a different time but i like that because of the daylight and we can speak about exercise timing at some point because there's a lot of discussion around that when is the right x time to exercise during sleep and we can sort of bust some myths there too um so i think you're spot on with the suggestion get some morning daylight try to get that exposure usually at least 30 to 40 minutes there was some great work recently coming out in the occupational health domain where they moved workers from offices that were just facing walls and you know didn't have any exposure to natural daylight and then they did a time period during that study where they actually were in front of a window and working and they measured their sleep and their sleep time and their sleep efficiency increased quite dramatically i'm forgetting the numbers now but i think the increase in total sleep time is well over 30 minutes and the improvement in sleep efficiency was 5 to 10 percent you know and if you're batting an 80 you know sleep efficiency average we're a bit concerned about that but add 10 percent to that now you're in you know a great echelon of healthy sleepers and all you did was just spend some time working in front of windows that's great and probably um folks might want to consider spending a little less time with sunglasses provided they can do that safely you know driving etc you're not alone with your exercise behavior and facing ease so um the one and only tim ferriss told me recently that his morning routine nowadays consists of jumping rope while facing east to get the sunlight stimulation of the eyes and um as matt and i both know it has to be of the eyes right yeah these portals are the only way to to um convey to the rest of the brain and body about the time of day and wakefulness um along the lines of wakefulness i have a number of questions about caffeine yeah the dreaded and beloved caffeine i love caffeine but i like it in relatively s um restricted periods of time so um i'm a big fan of waking up and even though i wake up very groggy allowing my natural wakefulness signals to take hold meaning i wake up very slowly but i don't drink caffeine right away i sort of delay caffeine by a little while usually 90 minutes to two hours okay and that idea came to me on the basis of my understanding of how caffeine and the adenosine receptor interact i have a feeling you're going to pronounce adenosine differently than i do no no i will go with it i'll go with the density i'll i'll try to go with your skeletal instead of skeletal synapse and shed you on schedule there we go but um but to make it really simple for folks how does caffeine work to make us feel more alert and does the timing in which we ingest caffeine play an important role in whether or not it works for us or against us so may we just start with how does caffeine work why is it that when i drink mate or coffee which are my preferred sources of caffeine do i feel a mental and physical lift yeah so i'm going to suggest counter to what most people would think drink coffee or mate is mate okay yeah yeah whatever form you will will come on to sort of why i suggest that but when it comes to coffee uh i would say the dose and the timing makes the poison so let's start with how caffeine works um caffeine is in a class of drugs that we call the psychoactive stimulants so it works through a variety of mechanisms one is a dopamine mechanism dopamine we often think of as a reward chemical or but dopamine is also very much an alerting neurochemical as well and caffeine has some role it seems to play in increasing dopamine but it's principal mode of action we believe in terms of making me more alert and keeping me awake throughout the day is on the effects of adenosine and to explain what adenosine is from the moment that you and i woke up this morning this chemical adenosine has been building up in our brain and the longer that we're awake the more of that adenosine accumulates is it um may i ask is it accumulating in neurons in glia or in the blood vessels where and and is it also accumulating in my body where is this adenosine coming from and where is it accumulating yeah so the adenosine here that we're talking about that is creating the sleep pressure is a central brain phenomenon and it comes from the neurons themselves combusting energy and as they're combusting energy one of the offshoots of that is this chemical adenosine okay and so as we're awake throughout the day and our brain is metabolically very active it's accumulating and building up this adenosine now the the more adenosine that we have the sleepier that we will feel so it really is like a sleep pressure is what we call it now it's not a mechanical pressure don't worry your head's not going to explode it's a chemical pressure and it's this weight of sleepiness that we feel gradually growing as we get into the evening may i just interrupt you again to just ask do we know what the circuit mechanism is for that i mean not to um go too far down the rabbit hole but for the aficionados and for myself uh we have brain mechanisms like locus ceruleous that release things that are brain areas locus thrillers just being a brain area of course that release things that create that proactively create wakefulness yeah so are those neurons shutting down as a consequence of having too much adenosine or are there areas of the brain that promote sleepiness that are being coming activated because these you can imagine both things working in parallel one or the other would accomplish the same endpoint yeah and it's it's both and so there are two main receptors for adenosine the a1 receptor and the a2 receptor and they have different modes of activating brain cells or inactivating or decreasing the likelihood of firing and adenosine works in this beautiful elegant way where it will inhibit and shut down the wake promoting areas of the brain whilst also increasing and dialing up the volume on sleep activating sleep promoting oh it's always a push pull yeah i mean we and we could have a larger discussion at some point about that um everything seeing dark edges seeing light edges uh yeah our ability to to smell or to sense pressure on this everything's a pushback that's a great yeah yep so this is another example where as i am awake longer adenosine is released in the brain and my wakefulness areas are being actively shut down by that adenosine and my sleepiness brain areas so to speak are being promoted to be more active is that correct that's right and it's a very progressive process it's not like a step function where and sometimes that happens occasionally but it's usually because you've been sort of driving through and as we'll come on to have caffeine in the system and then all of a sudden you just hit a wall and it just you know engulfs you and you go from a zero to the one of sleepiness within a short period of time explains the fatigue after a hard conversation the desire to go to sleep or the desire to go to sleep during a hard conversation um that's an interesting i think it's usually just based on personality type interactions and for the most part not that i've ever experienced that no people with you don't but with me they oh no no i mean i've experienced the desire to some conversations i'm halfway through them and i feel like i want to take a nap yeah right um and i would love to look at you know people's sleep history we've sort of seen that time and time again but um and then it could be you know with with folks like me people just lose the will to live within about five minutes of speaking with me so they hear that sleep is important it's unrelated and that's flattery that's great but so the way that then caffeine comes into this equation as i was saying it's usually a kind of a linear process or maybe it's probably closer to an exponential in terms of your subjective feeling of sleepiness and we haven't really been able to measure that in humans because normally we it's hard to actually you know stick something into the brain and be you know sucking siphoning off stuff every couple of minutes as you could do in animal studies and keep asking people every couple of minutes how sleepy do you feel how sleepy and track to see if there's a linear rise in you know adenosine which then creates an exponential rise in subjective sleepiness or what the dynamics are but i'm i'm kind of nerding out caffeine comes into play here because caffeine comes into your system and it latches onto those welcome sites of adenosine the adenosine receptors but what it doesn't do is latch onto them and activate them because if it was doing that then it would you know in lots of ways it would dial up more sort of sleepiness it does the opposite the way that caffeine works is that it comes in competes with quite sharp elbows with adenosine competitively forces them out of the way hijacks that receptor by latching onto it but then just essentially blocks it it doesn't inactivate the receptor it doesn't activate the receptor it functionally inactivates it in the sense that it takes it out of the game for adenosine so it's it's like someone you know coming into a room and you're just about to sit down on the chair and caffeine comes in and just pulls out the chair and you're like well now i've got nowhere to sit and caffeine just keeps pulling out the chairs from adenosine and adenosine even though it's at the same concentration in your brain your brain doesn't know that you've been awake for you know 10 hours 16 hours at that point when you've downed a cup of coffee because all of that adenosine that's still there can't communicate to the brain that you've been awake for 16 hours because but the adenosine is still in brain cells correct so so the real question is what happens when caffeine is dislodged from the adenosine receptor things happen and that's what we call the caffeine crash which is caffeine has a half-life and it's metabolized um and you recall what the half-life is yeah the half-life is somewhere between five to six hours and the quarter life therefore is somewhere between 10 to 12 hours it's variable different people have different um durations of its action but for the average adult five to six hours that variation we understand it's down to a liver enzyme or a set of liver enzymes of the class that we call the cytochrome p450 enzymes and there are two i think last i i delved into the data which is pretty recently there are two gene variants that will dictate the enzymatic speed with which the liver breaks down caffeine and that's why you can have some people who are very sensitive to caffeine and other people who say you know i'm just doesn't affect me really that much at all these are the people that have a double espresso after a 9 p.m dinner and you can sleep just fine well and we'll cover at least subjectively they think objectively yeah and we we should speak about that that assumptive danger too so then the caffeine is in the system and after some time period it will be inactive in the system so let's say that you know i've been awake for 12 hours now and it's you know 8 p.m and i'm feeling a bit tired but i want to push through and i want to keep working for another couple of hours so i have a cup of coffee all of a sudden i was feeling tired but i don't feel like i've been awake for 12 hours anymore because with the caffeine in the system maybe only half of that adenosine is being communicated through the receptor to my brain 100 of the the adenosine is still there only half of it is allowed to communicate to my brain so now i think oh i haven't been awake for 12 hours i've just been awake for six hours i feel great then after a few hours and the caffeine is starting to come out of my system not only am i hit with the same levels of adenosine that i had before i'd had the cup of coffee several hours ago it's that plus all of the adenosine that's been building up during the time that the caffeine has been in my system so sort of a an avalanche of it is a tsunami wave yeah and i have a caffeine crash and it's interesting because the caffeine crash at uh two o'clock in the afternoon when you have work to do is a terrible thing but what about the person maybe this person is me in my 20s who says i'm gonna drink caffeine all day long and then i want the crash because at 9 or 10 pm if i stop drinking caffeine at say 6 pm and i crash then i crash into a slumber a deep night of sleep is that sleep really as deep as i think it is because given the half-life of caffeine that you mentioned a few moments ago i have to imagine that having some of that caffeine circulating in my system might disrupt the depth of sleep or somehow the architecture of sleep in a way that even if i get eight or who knows even 10 hours of sleep it might not be as restorative as i would like it to be yeah and that is the danger just sort of that you know those people that you described who say and i a lot of them will um speak with me too say look i can have two espressos with dinner and i fall asleep fine and i stay asleep because usually those are the two phenotypes that we typically see with too much caffeine i just can't fall asleep as easily as i want to or i fall asleep but i just can't stay asleep and caffeine can do both of those things quite potently how late in the day do you think is assuming somebody translate this folks if you go to bed earlier or later you have to shift the hours accordingly but given somebody who typically gets into bed around 10 10 30 and falls asleep around uh 11 11 30 yeah when would you recommend they halt caffeine intake and these are not um strict prescriptives but i think people do benefit from having some uh fairly clear guidelines of what might might work for them would you say cut off caffeine by what time of the day i would usually say take your typical bedtime and count back sort of somewhere between ten to eight hours is probably getting a little bit close but take back sort of ten hours or eight hours of time that's the time when you should really stop you know using caffeine is the suggestion and the reason is because for those people who even just keep drinking up until you know the into the evening you're right that they can fall asleep fine maybe they stay asleep but the depth of their deep sleep is not as deep anymore and so there are two consequences the first is that for meat and it can be up to by 30 percent and for me to drop your deep sleep by 30 i'd have to age you by between 10 to 12 years or you can just do it every night to yourself with a couple of espressos the second is that you then wake up the next morning and you think well i didn't have problems falling asleep and i didn't have problems staying asleep but i don't feel particularly restored by my sleep so now i'm reaching for three or four cups of coffee the next morning rather than just two or three cups of coffee and so goes this dependency cycle that you then need your uppers to wake you up in the morning and then sometimes people will use alcohol in the evening to bring them down because they're overly caffeinated and alcohol and we can speak about that too also has very deleterious impacts on your sleep as well so you're right that it's not just the quantity of your sleep or even difficulties falling or staying asleep it can also be deep sleep but here again i think you know i don't want to be frightening people and i mentioned this before i think one of the real problems that i or mistakes that i made because i didn't you know i'd never had much public exposure before the book um and i was so saddened by you know the disease and the suffering that i was seeing as a consequence of a lack of sleep in our society and the fact that it wasn't really being discussed very much i sort of came out you know a little bit headstrong more than a little bit headstrong and i think i was you know perhaps too too much gas pedal and too little you know break as it were and i don't think that's the right way to approach health message within the public sphere and i've become much softer in how i think about these things i have ideas about what the ideal world looks like for sleep but i also realize that none of us live in this thing called the ideal world we certainly don't so you know i want to be really mindful of that and i think i've done a really bad job of being sort of too forthright particularly for people who struggle with sleep you know early on when i would offer these sort of messages about sleep i want to be you know i want to be veritical when it comes to the science i want to be faithful to the science but i also don't want to go out and scare the living daylights out of people particularly people who are struggling with their sleep because it's probably only going to make matters worse so i've been beautifully schooled by um learning how to be a slightly better public communicator i'm nowhere near understanding that that you are you're very elegant and it's very intuitive to you i'm still with training wheels but i'm getting a little bit better but i don't i just want to say that when i'm speaking about caffeine because it sounds as though i'm very um sort of overt about it but i will come back to why i say drink coffee um but i just want to make that point yeah well i appreciate you making that point and i'm sure our listeners will too um i i still will stand behind my statement um which is that what you've done for the notion that sleep is vital for all aspects of health and for performance mental and physical and wakefulness the message and that and the packaging it was contained in and is has been clearly clearly net positive people needed to be queued to this i'll sleep when i'm dead mentality is one that i had it's one that other people have um people in a huge number of vital communities not just your your students but also um people that this the messaging that you provided and continue to provide has positively impacted the first responder community the medical community there's still steps that need to be taken the military community and of course the civilian community and so i think these adjustments about yeah caffeine's okay just restrict it to the early part of the day if you can most days i mean i think the law of averages it's like the light viewing behavior i think it is critical to view sunlight or natural some other form of bright light early in the day but if you miss a day it's not that your whole system is going to dissolve into a puddle of tears that'll that'll happen on the second or the third day no i'm kidding you get a couple days biology works in averages except with respect to accident or injury a car accident is a car accident right you don't get to have three of those before the brain damage occurs if the accident is severe enough yeah but with sleep behavior these um homeostatic type behaviors or with food one chocolate sundae is it gonna kill you no every night yeah it's gonna make you demented and kill you early we know this and so i think the the middle ground is often a hard place to achieve um so i think you've done a phenomenal job but i appreciate you raising these points and and i think um it's clear that we all need to that we all can and should do certain things better including being gentle with ourselves from time to time when we deviate from these uh these ideal circumstances along these lines i i do want to talk about alcohol because i think caffeine and alcohol represent the uh the kind of two opposite ends of the spectrum clearly there are other stimulants um there are your adderalls and your uh high energy drinks that people use but alcohol and caffeine are the most commonly consumed yeah stimulants and and sedatives depressants as they're sometimes called so um what happens when somebody has a glass we always hear a glass or two of wine in the evening or a a cocktail after dinner yeah or before dinner how does that impact their sleep and then we'll be sure to circle back in terms of what is reasonable ranges of behavior when it comes to avoiding alcohol or if it's age-appropriate etc enjoying alcohol yeah so alcohol if we're thinking about classes of drugs they're in a class of drugs that we call the sedatives and i think one of the first problems that people often mistake alcohol is often used as a sleep aid for people who are struggling with sleep when things like over-the-counter remedies etc or herbal remedies have just not worked out for them and alcohol unfortunately is anything but a sleep aid the first reason that most people use it is to try and help them fall asleep and this process of this event that we call falling asleep i have to imagine is a process it is like everything in biology and that that process involves in some way as we talked about push-pull before turning off thinking planning etc and turning on some sort of relaxation mechanism i have to imagine that these two things are knobs turning in opposite directions this gives us this outcome we call falling asleep alcohol it seems is helpful for some people to turn off their thoughts or their planning is that right yes it is and so i think you know if we look at the pattern of brain activity if i were to place you inside an mri scanner where we're looking at the activity of your brain and watch you drifting off some parts of your brain will become less active other parts will become more active and this is the push-pull model it's inhibition excitation but alcohol is quite different in that regard alcohol is because it's a sedative what it's really doing is trying to essentially knock out your cortex it's sedating your cortex and sedation is not sleep but when we have a couple of drinks in the evening when we have a couple of night caps we mistake sedation for sleep saying well i always when i have a couple of whiskeys or a couple of cocktails it always helps me fall asleep faster in truth what's happening is that you're losing consciousness quicker but you're not necessarily falling naturalistically asleep any quicker so that's one of the first sort of things just to keep in mind the second thing with alcohol is that it fragments your sleep and we spoke about the quality of your sleep being just as important as the quantity and alcohol through a variety of mechanisms some of which are activation of that autonomic nervous system that fight or flight branch of the nervous system alcohol will actually have you waking up many more times throughout the night so your sleep is far less continuous now some of those awakenings will be of conscious recollection the next day you'll just remember waking up many of them won't be and so but yet your sleep will be littered with these sort of punctured awakenings throughout the night and again when you wake up the next morning you don't feel restored by your sleep you know fragmented sleep or non-continuous sleep in this alcohol induced way is usually not good quality sleep that you feel great on the next day the the third part of alcohol in terms of an equation is that it's quite potent at blocking your rem sleep your rapid eye movement sleep and rem sleep is critical for a variety of cognitive functions um some aspects of learning and memory it seems to be critical for aspects of emotional and mental health you've described it before as a sort of self-generated therapy that occurs while we sleep yeah it's overnight therapy you know it's emotional first aid uh certainly people that don't get enough sleep um are very easy to derail emotionally yeah not that one would want to do that to people but we all sort of fall apart emotionally are i i always think about almost like our skin sensitivity can be heightened yes when we are sleep deprived um our emotional sensitivity um is such that when we're sleep deprived such that it takes a um much finer grain of sandpaper to create that kind of friction yeah things bother us it thresholds even online comments bother us when we're sleep-deprived and never when we're i would love to say that i never look at them uh except i look at i should maybe everyone here i will editorialize because the notion of not looking at comments is um is unreasonable for to ask of any academic because academics we are all trained to look at our teaching evaluations yeah and just like with online comments to ignore 20 of them no i'm kidding we look at them all um in any event so in terms of translating this to behavior i'm not i don't particularly enjoy alcohol i guess i'm might be fortunate in that sense but i also have never really experienced that the pleasure of drinking uh alcohol i sometimes like the taste of a drink but i never liked the sensation so that's i don't have a lot of familiarity with this but many people do and i understand that so let's say um somebody uh enjoys a glass of wine or two with dinner and they eat dinner at 7 p.m is that likely to disrupt their sleep at all let's just sort of let's make this a series of gradations yeah and the answer is yes um i think one city just looked at a single glass of wine in the evening with dinner and i would be untruthful if i didn't just simply say it has an effect and we can measure that uh in terms of lesser obviously less rem sleep and one of the fascinating studies i can't remember what dose i think they got them close to a standard illegal blood alcohol level so maybe they were a little bit tipsy and yes you see all of the changes that we just described um they sort of lose consciousness more quickly they have fragmented sleep and they have a significant reduction in rem sleep but what was also interesting because rem sleep as we spoke about before is a time when some hormonal systems are essentially recharged and refreshed growth hormone being one of them there's well over a fifty percent five zero drop in their growth hormone release during alcohol laced sleep at night wow and growth hormone is so vital for metabolism and repair of tissues and yeah um essential um along those lines i i just want to highlight the fact that this um this information that you're sharing that growth hormone is released is strongly tethered to the presence of healthy amounts of rem sleep is interesting to me because i always thought the growth hormone was released in the early part of the night well it is released across both of those but across the different stages but what we also know is that when you disrupt rem sleep there are those growth hormone consequences so it's not an exclusive system just like with testosterone we can see changes throughout non-rem sleep but if you ask when are the peak release rates of testosterone it's right before we go into rem sleep and then during rem sleep and of course testosterone being important both for for males and females right for libido and tissue repair and well-being nobody regardless of chromosomal hormonal or any other background wants to have their normal levels of testosterone reduced acutely that's just a bad it it equates to a terrible set of psychological and physical symptoms yeah and the mortality risk that's associated with low testosterone is non-trivial prostate cancer right exactly you know so coming back to just the point on rem sleep that you mentioned regarding emotional instability and we see that that's one of the things one of the most reliable signatures of just insufficient sleep doesn't have to be sleep deprivation what we've discovered over the past 20 years here at the sleep center is that there is no major psychiatric disorder that we can find in which sleep is normal and so i think that firstly told us there is a very intimate association between your emotional mental health and your sleep health but when it also comes to rem sleep i think what's fascinating is that it's not just about your emotional health it's not just about your hormonal health um we've also been seeing other aspects of you know cognition but then there was a a report i think it could have been about two years ago out of harvard um i think it was beth clearman's group um they found that and they replicated it in two different large populations if you look at the contribution of different sleep stages to your lifespan rem sleep was the strongest predictor of your longevity and it was a linear relationship but wasn't it sort of one of these u-shaped or j shaped curves that we often see with total sleep and mortality risk it really was linear that the less and less rem sleep that you were getting the higher and higher your probability of death and then they did was that death due to um natural causes or accidents i could imagine if you're not getting enough rem sleep you're more likely to drive off the freeway step off a cliff yeah i think it was all cool just make bad decisions about anything like relationships yeah which can also be life-threatening yeah i've tried to lean into that and claim that i um with those bad relationship situations that oh i just didn't have enough last night my darling yes and uh but uh she's far wiser than i thought but um so they did this great machine learning analysis and i may get these numbers backwards but i think for every five percent reduction in rem sleep there was a 13 associated increased risk of mortality and i could have i'll have to go back and and check but to me and in the machine learning algorithm what they ultimately spat out was that of all of the sleep stages rem sleep is the most predictive of your longevity of your lifespan so we often i hear people saying how can i get more deep sleep or they sometimes say how can i get more dream sleep and my answer is a question why do you want to get more of that and they'll say well isn't that the good stuff and i'll say well actually all stages it's all the good sleep yeah well it's like the exercise question and it took decades for people to understand that moving around at for about 150 probably 180 minutes a week at doing endurance type work zone 2 cardio type work it is correlated with living longer feeling better less diabetes etc there's really no way around it i mean you can um you can ingest metformin until the cows come home you can take nmn all of which i think have have their place in certain contexts i'm a big fan of the work surrounding all those protocols but without getting proper amounts of movement meaning sufficient numbers it doesn't matter how many 12-minute exercise regimes you follow per week you need that threshold level and it sounds like the same is true of rem sleep and total amount of sleep there's just you um you pay the piper somehow yeah the return on investment i mean to flip the coin the return on investment is is astronomical you know i think of sleep it is the tide that moves you know that raises all of those health boats and the most fundamental layer of mental and physical health whenever people ask me even though i'm not a physician they'll ask me what what should i what should i take or what should i do the first question is always how's your sleep greening how well do you sleep every night and and how how long do you see my always recommend your book i always recommend your podca your you know the podcast you've been uh a guest on et cetera um who knows maybe you'll even release your own podcast at some point soon and keep because i do think people need to hear from you more often one thing i i don't want to return to the the notion of of public health discourse too much but i do want to say one issue with books in general is that they can be revised but it's more or less a one and done kind of thing until the next book comes out yeah one thing that i like about the podcast format is that updates can be provided regularly corrections and updates as new data come out and so that's a wonderful aspect to this format and and uh hopefully the format that you'll be embracing i think the world needs to hear more from you more often about sleep and its various contours um not less and so i do have a question about uh drinking alcohol not that we want to promote day drinking but let's say that the one or two glasses of wine or cocktail is consumed with lunch something that isn't traditionally done nowadays or in a late afternoon happy hour type cocktail and then one is going to sleep seven or eight hours later do you think that that will improve or somehow mitigate the effects of alcohol or if you have a drink are you basically screwed for the next 24 hours no i think there's going to be a time window dependency now i don't know of anyone who's essentially done what you and i would like which is the time separation dose dependent curve were okay you drink at 10 a.m then or 11 12 1 2 3 4 5 all the way up to you know 10 pm and estimate what is the blast radius and is it linear or is it non-linear is it such that only when you drink in the last four hours do you just hit this exponential and it's bad bad bad or is this some other curve that we could imagine there would be many possibilities but certainly what we know is that the less alcohol and the less and more specifically the metabolic byproducts aldehydes and ketones they're the sort of the nefarious players and not the ketones that people are all excited about the other the other ketones yes the chemists know what we're referring to but this is not about kisogenesis this is not about ketogenesis there are ketone bodies and uh that are released uh after ingesting alcohol that are not of the positive sort correct that uh a ketogenic diet might promote right yeah so i think in terms of that alcohol um profile we certainly know that you know as you're heading into the evening hours once again timing and dose make the poison but i think it's also important once again from that public uh message standpoint and thank you i think i i i am leaning into the sort of the podcast uh consideration arena at some point but i don't want to be puritanical here you know i'm just a scientist and i'm not here to tell anyone how to live all i'm trying to do is empower people with some of the scientific literature regarding sleep and then you can make whatever informed choices that you want now unlike you it turns out i'm not a big drinker it's just because i've never liked the taste and i'm surprised that they haven't taken away my british passport because i don't like lager or beer but i also want to say that life is to be lived to a certain degree it's all about checks and balances so you know if i go out and you know i have an ice cream sundae i'm not big on those either but you know sure i know that my you know blood glucose is not going to be ideal for another 12 hours maybe that's just the price you pay for having some kind of relaxed fun life i don't want to look back on life and think gosh you know i lived until i was you know 111 and it was utterly miserable you know right so but it's all about some kind of a balance and mine my job is not to to tell people um a prescription for life it's just to offer some scientific information oh i think you're doing a terrific job of that p people are i always say we have all these neural circuits and um if it's working properly we all have a circuit that allows us to uh skip over information or as we wish right if the circuits between your brain and your thumbs are working you can slide right along you can drop to the next content however you like i i would like to ask about marijuana and cbd this is a discussion that i think five years ago would have ventured into the realm of illegal but now yeah in many places not all medical marijuana is approved or is legal and certainly it's in widespread use certainly not recommending people do it i have my own thoughts about marijuana cbd i've been fortunate i suppose that i don't particularly like marijuana or cbd i don't even know if i've ever tried cbd um first of all does marijuana disrupt the depth of sleep the architecture of sleep and if so as with alcohol and caffeine does when you ingest it or when it's in your bloodstream does relative to when you go to sleep does that play an important role so does marijuana disrupt sleep yeah it it does and there's a pretty good amount of data on so we can break uh sort of cannabis down into two of its key ingredients we've got thc tetrahydrocannabinol and we've got cbd and cbd is sort of the the less psych what's it what we think of as the non-psychoactive component in other words when you take cbd you don't get high if you take thc you can get high that's the psychoactive part of the equation are both considered sedatives in the technical sense uh no they're not neither of them have that class right now thc can seems to speed up the time with which you fall asleep but again if you look at the the electrical brainwave signature of your falling asleep with and without that thc it's not going to be an ideal fit so you could argue it's non-natural but many people use thc for that fact because they find it difficult to fall asleep and it can speed the onset of at least non-consciousness i guess is the best way of describing it but there are problems with thc and there are twofold the first is that it too but through different mechanisms seems to block rem sleep and that's why a lot of people when they're using will tell me look you know i i definitely i was dreaming i don't remember you know many of my dreams and then when they stop using uh thc they'll say i was having you know just crazy crazy dreams and the reason is because there is a rebound mechanism rem sleep is very clever and alcohol is the same way in this sense it's the same homeostatic mechanism some people will tell me look if i have a bit of a wild friday night with some alcohol you know maybe i'll sleep late into the next morning and i'll just have these really intense dreams so and i thought i wasn't having any rem sleep well the way it works is that it's during in the middle of the night really when alcohol blocks your rem sleep and your brain is smart it understands how much rem sleep you should have had how much rem sleep you have not because the alcohol has been in the system and finally in those early morning hours when you're getting through to sort of you know six seven eight a.m all of a sudden your brain not only goes back to having the same amount of rem it would have had it does that plus it tries to get back all of the rem sleep that it's lost does it get back all of the rem sleep no it doesn't it never gets back all of the rem sleep but it tries and so you have these really intense periods of rem sleep hence you have really intense bizarre dreams and that's what happens also with thc you build up this pressure for rem sleep this debt for rem sleep will you ever pay it back it doesn't seem as though you get back everything that you lost but will you get back some of it yes the brain will start to devour more because it's been starved of rem sleep for so long but one of the bigger problems with thc that we worry about is withdrawal dependency so as you start to use thc for sleep there can be a dependency tolerance so you start to need more to get the same sleep benefit and when you stop using you usually get a very severe rebound insomnia and in fact it's so potent that it's typically part of the clinical withdrawal profile from thc from cannabis and there's anxiety withdrawal i i've um i i you know i don't ask anybody to change their behavior we just as you said we try and inform people about what the science says and and let them make choices for themselves people who are regular uh pot smokers if you that many of will insist they're not addicted and and maybe indeed they don't actually follow the profile of classical addiction i don't know i'm guessing some do some don't but if you ask them well what if i took away all marijuana consumption for i don't know two weeks that thought scares many of them and many of them will experience intense anxiety without marijuana which speaks to perhaps not addiction but a certain kind of dependency um and again i i you know i know many pot smokers um some of whom uh have jobs that are that are quite high performing and they and they manage here in berkeley i don't know any of those right um the what about cbd i mean we hear so much about cbd i've been a little concerned about the fact that um the analysis of a lot of cbd supplements out there is confirmed that much like with melatonin the levels that are reported on the labels in no way shape or form match the levels that are actually contained in the various supplements sometimes the levels are much higher than they're reported on the labels other times it's much lower um what does ingesting cbd do to the architecture and quality of sleep right now i don't think we have enough data to make some kind of you know meaningful sense out of it i think the picture that is emerging however is probably the following firstly cbd does not seem to be detrimental in the same ways that thc is so we can start by saying it does it create you know potential problems not of the the nature necessarily that we see with thc but the devil is a little bit in the details from the data that we do have and it comes onto your valid point of purity at low dose cbd can seem to be wake promoting so in lower doses let's say sort of five or ten milligrams i'm trying to remember some of the studies off the top of my head there it actually may enhance wakefulness and cause problems with sleep it's only once you get into the higher dose range that there seem to have been some you know increases sorry increases in sleepiness or sort of sedation-like increases and that's usually i think above about 25 milligrams as best i can recall from the data and then when we look in animal models you typically see the same type of profile too so then the question becomes and now again you just don't know about you know purity it's very difficult although i think and again i'm i'm not a user not necessarily because i you know have anything against it it's just that's not you know necessarily my cup of tea there are some firms that are now doing third-party independent laboratory tests i don't know how gamed that is so i've got no sense i think some supplement companies are quite um honest and accurate about the amounts of various substances that are in other uh products and some are not yeah and i think there's just a huge range i think the fda is starting to explore cbd there are i certainly i saw some grant announcements to explore the function of cbd most of the work on cbd is being done by the general public ingesting it and saying how they feel i gave it to my dog who was had some uh dementia related sleep disturbances and it actually created a heightened wakefulness it completely straight up sounds as though he's a bulldog so he's gonna get access to sleep he's gonna take it okay um really messed him up took him took it away he did better um but you know that's that's a canine so right and it could have been you know sort of dose-related too but or binders or other things that are in there correct yeah and we but right now if we were to and i'm not making this statement i don't think anyone could make the statement now but if it ends up being that cbd is potentially beneficial for sleep how can we reconcile that mechanistically and i think there are to me at least there are at least three candidate mechanisms that i've been exploring and thinking about the first is that it's thermoregulatory and what we found in some animal models is that cbd will create a profile of hypothermia in other words it cools the body the core body temperature down and that's something that we know is good for sleep the second is that it's an anxiolytic that it can reduce anxiety and that data is actually quite strong even with some functional imaging work that's been coming out recently showing that one epicenter of emotion called the amygdala deep within the brain is quietened down with cbd so i think that's at least a second non-mutant that's great that's exclusive you know possibility i think the third um is some recent data that's come out that was suggesting that cbd can alter the signaling of adenosine so it doesn't necessarily mean that you produce more adenosine but what it can do is perhaps modulate the sensitivity perhaps of the brain so that the weight of that same adenosine is weightier in its brain signal and therefore it creates this stronger pressure for sleep so i think these are all tentative mechanisms i think any one of them is viable i think all three are viable together but right now i think does that sort of help think through the the tapestry of thc and cbd yeah very much so and actually it's a it's a perfect segue from we've talked about caffeine alcohol thc and cbd as sort of uh we framed them anyway as things that done in moderation at the appropriate times are probably okay for most people certainly not for everybody there will be differences in sensitivity but that done at the incorrect times and certainly in the incorrect amounts will greatly disrupt this vital stage of life we call sleep cbd it seems represents a kind of bridge to the topic i'd like to talk about next which is things that promote more healthy sleep or somehow contribute to enhancing the architecture and quality of sleep so i'd love to chat for a moment about the kind of grant the original i should say that not the granddaddy but the og of sleep supplementation which is melatonin yeah the so-called hormone of darkness uh that's inhibited by light etc frame for us melatonin in the context of its naturally occurring form and then i'd like to talk about melatonin the supplement because as in my experience anytime i say the word melatonin people think about the supplement melatonin which in itself is an interesting um uh phenomenon that people are so cute to its role as something you take we often forget that this is something that we make endogenously i'd love for you to comment in particular on even though we without necessarily getting into precise nanograms per deciliter values what are the typical amounts of melatonin that we release each night and then i'd like to compare that to what is contained in say a three milligram or six milligram tablet that one might buy at the pharmacy right so i go to sleep at night has melatonin already kicked in before i shut my eyes and lay down my head usually yes if your system is working in the correct way as dusk is starting to happen so let's say that you look at hunter-gatherer tribes who aren't touched by electricity and so they're sort of the pure technical state par excellence when it comes to electric uh light influence um and usually it's as dusk is approaching that's when melatonin will start to rise and so when you lose the brake pedal of light coming through the eyes that normally acts like a hard brake pedal that stamps down and prevents the release and production of melatonin as that light break pedal starts to fade with dusk then we ease off the brake pedal and melatonin the spigot of metal melatonin is opened up and melatonin starts getting released and usually we'll see this rising peak of melatonin um sometime usually an hour two hours later or around and it varies from different people around the time of sleep itself but it's already been on the march for some hours before you actually hit sleep itself interesting and uh i was always taught and i'm assuming it's still true that the only source of melatonin in the brain and body is the pineal gland is that still true yeah it seems to be from best that we can tell and the pineal gland um sort of meaning p like sort of uh shape it's actually i think usually people say it's p like i think if you look at the latin derivative it's more um i think it's derived from pine cone not p because in fact if you look at the pineal it is more pine cone shaped and so it's aptly named any human brain i've ever dissected or i confess i've dissected a lot because i teach neuroanatomy and have for years um i i love looking at the pineal it's the one structure in the brain that's not on both sides it's usually pretty easy to find and it's pretty good size it looks like a it looks like a pea and it's sitting right there and it's remarkable that it releases this hormone probably our entire lifespan and is inhibited by light the um so our pineal starts to release this into the general circulation i have to imagine we have melatonin receptors in the brain and body correct so yeah essentially your brain has a central master 24-hour clock called the suprachiasmatic nucleus that keeps internal time now it's not a precise clock if left to its own devices nothing that a swiss clockmaker would be proud of it runs a little bit long and laggy it's like an american clock so there are a couple good american watches by the way hamilton's are very it's very much like a boat we're not famous for our time keeping or our punctuality for them but the swiss are it's very it's it's not quite swiss like it's more berkeley like which is very relaxed oh you know whatever um so in most adults of the average adult i should say your biological clock normally runs a little bit long it's about about 24 hours and 13 minutes i think was the last calculation but the reason that we don't keep drifting forward in time and kind of running consistently you know more and later and later 30 minutes by 30 minutes by 30 minutes each day is because your central brain clock is regulated by external things such as daylight and temperature as well as food and activity all of these are essentially different fingers that come along and on the wrist watch of the 24 hour clock will pull the dial out and reset it each day to precisely 24 hours and i make that point because it knows 24-hour time but it needs to tell the rest of the brain and the body the 24-hour time as well and one of the ways that it does this is by communicating a chemical signal of 24-hour nurse of light and day using this hormone melatonin and when it is at low levels or it's non-existent it's communicating the message it's daytime and for us diana's species it says it's time to be awake yet at night time when dusk approaches and the break comes off melatonin and we start to release it then it signals to the rest of the brain and the body look it's dusk and it's night time and for us die in all species it's time to think about sleep so melatonin essentially tells the brain and the body when it's day and when it's night and with that when it's time to sleep when it's time to wake and therefore that's why melatonin helps with the timing of the onset of sleep but it doesn't really help with the generation of sleep itself and this is why we'll come on to what those studies of supplementation have taught us so it tells the rest of my brain and body it's time to go to sleep it perhaps even aids with the transition to sleep but it's not going to for instance ensure the overall structure of sleep or um it's not the conductor that's guiding the sleep orchestra so to speak throughout the entire night yeah it's it's more like the um the people that essentially take you to your seat and sit you down and give you your program right exactly yeah sort of the the the far um less sophisticated analogy i have is um you know melatonin is like the starting official at the hundred meter race in the olympics that's a better analogy calls all of the the sleep races to the line and it begins the great sleep race yeah better discoloration coming from the sleep researcher but it doesn't participate in the race itself that's a whole different set of brain chemicals and brain and brain regions which then brings us on to perhaps the question of supplementation which is is it helpful for my sleep will i sleep longer will i sleep better and if i am what doses should i be taking sadly the evidence in healthy adults who are not older age suggests that melatonin is not really particularly helpful as a sleep aid i think there was a recent meta-analysis that demonstrated when um it it looked at all of the different sleep parameters melatonin and a meta-analysis for those not knowing what that is it's a scientific sort of method that we use where we gather all the individual studies and we put them in a big bucket and we kind of do this kind of statistical fancy sleight of hand and we tried to come up with a big picture of what all of those individual studies tell us and what that metro analysis told us is that melatonin will only increase total amount of sleep by 3.9 minutes on average minutes minutes no and it will only increase your sleep efficiency by 2.2 percent so it really is as as uh they say in um certain parts of california it's weak sauce that's a weak sauce effect it the the source is not strong the force is not strong in in this one when it comes to a tool that in healthy people who are not of older age it doesn't seem to be especially beneficial now you know results can vary everyone is different of course so we're talking about the average the so-called average human adult here well melatonin um in defense of what you're saying and also i should mention i have a colleague at stanford uh jamie zeitzer oh wonderful chuck zeisser's lab at harvard medway we also trained a terrific sleep researcher and i asked him about melatonin and he essentially said the same thing that you just said which is very little if any evidence that it can improve sleep and yet it's probably the most um commonly consumed so-called sleep age hundreds of million dollars industry yeah so either massive placebo effect or it's operating through some other mechanism related to quelling anxiety yeah that is actually interesting you know there are some studies where you do see some you know effects now again when you do the grand average of all studies it just doesn't seem to have an effect but let's assume that for some people it does have an effect let's not again be sort of completely dismissive of that how could it have that effect one of the reasons that i've become a little bit more bullish on melatonin from a sleep perspective and then melatonin more generally for a maybe we can speak about this too as a counter measure on when you're undergoing insufficient sleep um there are two two different routes there the first reason that i think it could have a sleep benefit for some people is not because it helps in the generation of sleep we know that it doesn't it's because it too seems to drop core body temperature there it is again i'm fascinated these days more and more by temperature as um maybe not just a refl a reflection of brain state and wakefulness and in sleep but actually a lever that uh is quite powerful i think it's both and with all the interest in ice baths and hot showers and saunas and stuff something that we will definitely touch on temperature variation is so key so if if melatonin is dropping body temperature by a degree or so something that you've said before can help induce a sleepy state maybe that's what's allowing people to get it and that's one possibility i i don't think melatonin by itself will drop it by sort of you know a a degree certainly not a degree celsius and for order in us to fall asleep and then stay asleep across the night we do need to drop our core body temperature by about one degree celsius or about two to three degrees fahrenheit and that's why it's always easier to fall asleep in a room that's too cold than too hot i think that that's one potential avenue that we are considering thinking more deeply about when it comes to melatonin and then the other is melatonin as an antioxidant but let's let me table that for now because i'll just get us sidetracked that's what we know so far about melatonin in terms of its supplementation benefit or lack thereof two final points that i shouldn't forget one is the only population where we typically see some benefit and it often is prescribed is in older adults because older meaning 60 and older yeah 60 65 and older because as we get older you can typically have what's called calcification of the pineal gland which means that that gland that's releasing melatonin doesn't work as well anymore as a consequence they tend to have a flatter overall curve of melatonin released throughout the night it's not this beautiful lovely peak and this bullhorn message of it's darkness please get to sleep that's why older adults can have problems falling asleep or staying asleep it's not the only reason by sure any stretch of the imagination but it's one of the reasons and it's why melatonin supplementation in those cohorts older adults especially older adults with insomnia people have thought about that as maybe an appropriate use case along those lines if we were to compare dosages i don't or do we know how much melatonin is typically released into the bloodstream per night um and can we use that as a kind of a rule of thumb by which to compare the typical amount that someone would supplement i mean typically the supplements for melatonin that i see in the pharmacy and elsewhere and online range anywhere from one milligram to 12 or even 20 milligrams my guess is that a normal night's release of melatonin typical for somebody in their 20s 30s 40s would be far lower than that am i correct or wrong yeah it's it's a many magnitudes lower and this is one of the problems is that i see that too i see you know typical doses are you know five milligrams or 10 milligrams and of course you know if you're a supplement company you know putting 10 milligrams versus 5 milligrams if that's what you're actually doing which we'll speak about purity as well um you know it's kind of like the super gulp size nobody wants to lower price they just want you to you know we'll just give you more for the same price and that's how we'll compete so it's been this escalating arms race of melatonin concentration and it really does not look meaningful for you know for sleep in any way what we've actually found is that the optimal doses for where you do get sleep benefits in the populations that we've looked at are somewhere between 0.1 and 0.3 milligrams of melatonin in other words the typical doses are usually 10 times 20 times maybe more than what your body would naturally expect and this is what we call a supraphysiological dose in other words it's far above what is physiologically normal you know and to put that in context imagine i said to you i want you to eat 20 times as much food today i thought you're going to use testosterone as an example you're going to take 300 times the normal amount of testosterone we know that would have um tons of deleterious effects very terrible yeah and yet you can do this what one thing that i'm concerned about about these supraphysiological levels of melatonin is that many years ago actually here at berkeley when i was a graduate student we would inject animals which were seasonally breeding animals with melatonin and the consequence of that was that their uh gonads either their testes or ovaries would shrink many hundred hundred fold or more um in other words they would go from having nice healthy sized hamster testicles what a hamster would consider healthy size um for a hamster and they would shrink to the size of a grain of rice so from like an almonds to a grain size of a grain of rice i had to see that only once for me to be very concerned about super physiological levels of melatonin and i realized that melatonin does different things in different species we are not hamsters we are not seasonal breeders uh seasonally restricted breeders there might be more breeding during certain seasons i don't know those data but nonetheless hormones are powerful and and sure there is an optimal and sometimes uh we see that going slightly above endogenous levels for certain hormones not always can have beneficial effects and sometimes it can have detrimental effects i'm just concerned about taking high levels of a hormone that has effects on the reproductive axis and that's one of the reasons why i get very concerned when i see people really getting aggressive about melatonin supplementation taking a hundred ten five hundred sometimes even ten thousand times the amount that we would normally release that's that's my concern although it's not nested in any one specific human study i just i just don't like to see i certainly don't want to see other people and i don't want to personally take a hormone that's known to be androgen suppressive at high levels why would i why would i take that right that's the question i ask myself i think it's a very you know good point and if you look at some of the evidence around you know melatonin's lethality if you want to go to that extreme for the most part you know it it's pretty safe the the you mean you can take a lot of it before you die right exactly yeah but i don't know that's that's not going to be your yardstick because you know you really need to think about your you know your health not just whether this thing is going to to kill you or not as the decision matrix through which you pop a pill and it comes on to this concern around melatonin because there was a study i think it's one that you mentioned too where they looked at over i think it was at least over 20 different brands of melatonin supplements and what they found is that based on what it said on the bottle versus what was in the capsules themselves it ranged from i think it was 83 less than what it said on the bottle to 478 more than what it said on the bottle now if you're if that's a 10 milligram you know pill and it's 478 more than 10 milligrams and we're already at 10 milligrams at many tens of times more than is a physiological rather than a supra physiological dose yeah we do need to be a bit thoughtful yeah remember those hamsters folks uh well and i do appreciate the deep dive on melatonin because i think people need to understand that it's it's nuanced it's a matter of dosages and timing etc and then it may have its place as you mentioned in older individuals and i should mention that i i'm an avid consumer of supplements that i believe in for me and i have been for a very long time so i'm by no means anti-supplement um some supplements i refuse to take or avoid taking others i am uh quite avidly take and along those lines i personally uh and i don't know uh what your thoughts on this are but there are a few things that i've personally found beneficial i'd love your thoughts on them and i would love it if you would tell me that uh everything i'm about to refer to as placebo that would be fine so um that's what we do we're scientists we argue and then and then we um we remain friends in uh as it goes so um magnesium there are many forms of magnesium magnesium citrate is a as we know is a terrific laxative uh magnesium malate seems at least from a few studies seems to relieve some of delayed onset muscle soreness doesn't seem to create a kind of sedation two forms of magnesium that i'm aware of magnesium by glycinate and magnesium three and eight yeah we believe based on the data can more actively cross the blood-brain barrier so you put in your gut but some of that needs to get into your brain in order to have the sedative effect what are your thoughts on magnesium supplementation do you supplement with magnesium and um what what studies would you like to see done if they haven't been done already so i don't supplement with magnesium but i do think threon8 is interesting because of that higher capacity to cross the brain barrier and actually have a central nervous system effect and the reason that that interests me is because the sleep is by the brain of the brain and also for the brain as well as for the body we just don't have a particularly good set of studies that have targeted exclusively three and eight we do have lots of studies that have just looked at magnesium in general for sleep and overall the data is uncompelling interesting and for a while i i was confused as to why where did this come from this kind of myth of magnesium so i started looking back into the literature and i've best traced it at least as far as i can tell to early studies showing that those who are deficient in magnesium also had sleep problems they had other problems too of course but sleep problems were one of that set of sequelae that came from having lower magnesium and when they supplemented with magnesium and tried to restore those levels some of those sleep problems dissipated and then that seems to have gotten lost in sort of some game of sort of like whispers around the room and it's become translated into people who don't have sleep problems who are healthy sleepers and who are healthy in general and who have healthy normal levels of magnesium if they take more magnesium they will sleep better and the data really there is not good once again the only study that i've seen where magnesium did have some efficacy was in a study with older adults i think they were 60 to 80 years old it may have been exclusively women now i think about it and they also had insomnia and in that population you did see some benefits and my guess is that because it's an older community as well they were probably probably deficient in magnesium so they fit the former category of simply when you're deficient and you restore you can help sleep sort of return to normal but if you are not deficient and you're healthy and you're not old and you don't have insomnia and you're supplementing thinking that it provides sleep right now the data isn't supportive of that but i just don't think we have enough three and eight data to actually speak about that because it could just be a blood-brain barrier issue so far with the other forms so maybe some additional studies looking specifically at three and eight or by glycinate would be would be unless we have magnesium's involved in so many cellular processes you can imagine that this effect if it truly exists is uh as we say in science in the noise meaning it's in the it's in the the jitter of the data but to isolate the real effect one needs to do some more refined studies um what are some things that are of interest to you if not things that you happen to take um these are not things that i personally take mostly because i just haven't experimented with them valerian root is one um tart cherry and kiwi fruit tell me about tell me about valerian root tart cherry and kiwi fruit this is new to me um i've certainly heard of them and um tart cherry and kiwi sounds delicious but what what's happening with valerian root tart cherry and kiwi and are we talking about eating tart cherries and kiwis and valerian roots you're talking about taking them in pill form usually it's supplements but it's also both for tart cherries and for kiwis it's the actual you know fruit themselves valerian often touted as a beneficial sleep aid and lots of people swear by it too but the evidence is actually quite against that oh really not that it makes your sleep worse but of at least the seven good studies that i've been able to find and typically these are of the nature of what we call a randomized placebo crossover design and i won't bore people with what that means it's sort of one of the studies solid yeah it's one of the sort of gold standard methods that we have when we're looking at intervention studies such as drug cities five of the seven found no benefit uh a valerian root on sleep then two out of the seven the data was just insufficient i think it was a power issue where they just couldn't make any strong conclusions and then i think there was the most recent study i think looked at two different doses of valerian i could have this wrong and they just failed to find any effects once again but the stunning part of that paper as i recall they had this big table with all of the different sleep metrics that they looked at and there were well over 25 different things that they tried to see if valerian impacted and none of them were significant which stuns me because from statistical probabilities we know if you just randomly perform 25 statistical tests chances are probabilistically you'll just get one significant result by random chance and even with random chance on their side they still couldn't find a benefit of valerian so so valerian root might be worse than nothing at all if there is uh so to speak i mean again placebo effect we can think about that too and i would say that if you feel as though it's having a benefit for you and with all of the caveats that we have with supplements things like melatonin purity concentration etc you know maybe it's no harm no foul but i'm not a you know a medical doctor and i don't tell anyone about we have all of these disclaimers about not recommendations and we'll include these things i mean i always say you know we're not physicians we don't prescribe anything we're scientists and professors so we profess things it's up to people to be responsible for their own health not just to protect us but to protect themselves um i i do want to hear about tart cherry kiwi fruit um what what's the story there strange isn't it i was you know i i'm kind of a hard-nosed scientist and when people you know some years ago started saying oh tart cherries it's the thing or kiwi fruits i was thinking oh my goodness this sounds good in california yeah i know yeah the sun has softened me uh some but i thought look one of the things that we have to do as scientists is be as open-minded as possible and i should not be so quick to dismiss so i went to the literatures just started reading as much as i could about it and there were three really good randomized placebo crossover trials with tart cherries and what they found was that in one study it reduced the amount of time that you spent awake at night by over an hour and then the other two studies one of them found that it increased the amount of sleep that you got by 34 minutes the other it increased the amount of sleep that you got by 84 minutes wow which you know these are and what's striking is that they were independent uh studies i think meaning that they were from independent groups and these were you know some of these guys you know i i and girls i know pretty well mm-hmm you know and trust their work right i really trust their work too are they ingesting actual tart cherries or they're drinking the juice or in capsule it was juice so they in all three studies it was juice although you can i think as a supplement you can buy it in a capsule and we've got no idea whether that changes the benefit or not what was also interesting in i think it was that last study where they got an increase in sleep by 84 minutes it also decreased daytime napping significantly that's one that i could certainly make use of so i'm i love you you know but i'd love to skip them too right and we can speak about naps and such of the upside and downside of that which then made me think well if that's the case maybe the net net benefit on sleep overall is no different it's just that it decreases the amount of time that some people were taking to sleep during the day and giving it back to the night but that wasn't the case because if you added the total amount of sleep that they were getting without tart cherries both naps and nightly sleep combined still when you took tart cherries you still got a net some benefit total amount of sleep so you know so far when it comes to supplements and those types of studies they're good studies and the data looks interesting but as a drug itself you know if this was clinical drug you know three studies that are somewhat small in nature and have some positive benefit that's what we would call preliminary data of maybe a chin scratching kind so yeah and depending on the margins for safety one might think well given that it's a tart cherry as opposed to some pharmaceutical you need a prescription for then uh you know some people their threshold to experiment with supplements is quite low some people their threshold is quite high i feel like you know there are two categories or at least two categories of folks out there people who hear oh tart cherry can improve sleep and we'll run out and try it and people who hear well that sounds crazy why would i do that um but of course we have to remind people that tart cherry isn't really what we're talking about presumably if this is a real effect and sounds like it might be that there's a compound in tart cherry that's right that if we were to call it whatever whatever five alpha six you know some molecule if we refer to it by its technical name then people would say oh that sounds like a very interesting technical way to approach sleep but doesn't sound very natural so both groups are a little bit um misguided in the sense that people who think that everything that comes from naturally occurring foods plants etc things that grow out of the ground that that's all safe that's not true and people that think that pharmaceuticals are the only if it's not evidence with the purified molecule then something's not of utility well that's certainly not true somewhere in the middle i think lies the answer which is sounds to me like tart cherry is at least an intriguing potential sleep aid intriguing potential sleep aid and underscoring potential um i'm certainly intrigued by it to the point where i i might experiment a bit but i'm an experimenter for myself um before i uh ask you about kiwi uh i've had quite good results from taking something called apogenin which is a derivative of chamomile but in supplement form i think i take 50 milligrams about 30 minutes before sleep and i subjectively experience a a better night's sleep so to speak i don't measure i confess i don't measure my sleep i'm not a sleep tracker guy um but uh you know there are a few papers out there they're not what we would call blue published in blue ribbon journals but but they have control groups and it looks somewhat interesting and there when i say apogenin uh people get somewhat intrigued oh this molecule chamomile has long been thought to be a sedative a mild sedative but a sedative do you drink chamomile tea do you take apogenin what are your thoughts on epigenetics yeah i i don't and i i have looked into some of the data regarding sleep as well right now from best i can tell it's mostly subjective data rather than objective hard sort of sleep measures and that's why right now i you know it's sort of unclear not no comment but just unclear not dismissing it because i think you and i both ascribe to the idea of absence of evidence is not evidence of absence so keep your mind open at least i tell that to myself [Music] i think if you're finding a benefit and you can do what i would think of if i was personally experimenting which is both the positive and negative parts of the experiment what i mean by that is you know let's say that i now want to you know think about some kind of a sleep supplement i will take some kind of baseline set of recordings for a month and i will just gauge where i'm at sort of supplement free then i'll go on for a month to whatever i'm thinking of taking and i don't you know supplement but let's say that i want to and i experiment with that and i feel as though based on my metrics be them objective from my aura ring or be them subjective from whatever i'm you know writing down in the morning and both are important valid subjective and objective we like both in the sleep world and i think okay look it's clearly that it seems to have some kind of an effect the key thing however is then do the negative experiment which is now come off it for another month and see do things get worse and if i can see that bi-directionality then i am starting to think maybe i'm believing this a little bit more so that's the way i would sort of typically approach you know a supplementation regiment if i were to do it and that's just me that's just the way my mind works but no that's great i think it's very very scientific and organized in a way that allows uh you and and would allow other people to make very informed decisions for themselves um i like that i um i like to think in terms of of manipulating any aspect of our biology that behavioral tools always are the first line of entry then nutrition everyone has to eat sooner or later even if you're fasting then perhaps supplementation then prescription drugs and then perhaps brain machine interface devices that you use to induce something and those could be done in combination but what concerns me is when i hear people uh say well what should i take without thinking about their behavior their light viewing behavior et cetera but of course these things work in combination uh i think it's you're right that there's many when it comes to sleep there are many low-hanging fruits that don't necessarily require you to you know put sort of exogenous molecules in other words things like supplements into your body or you know use different types of drugs to help you get there now when it comes to prescription sleep aids i think i've been again a little bit too forthright we know in clinical practice that there may be a time and a place for things like sleeping pills they are a short-term solution to certain forms of insomnia but they are not recommended for the long term and we also know that there are lots of other ways that you can get a sleep help or you can get a sleep curative profile from things like cognitive behavioral therapy for insomnia which is a non-drug approach psychologically quite effective from what i understand just as effective as sleeping pills great data more effective in the long term there's a recent study published that after working with that therapist some of the benefits lasted almost a decade you know now if you stop sleeping pills usually you have rebound insomnia where your sleep goes back to being just as bad if not worse and i think the same is true when we think about supplementation there are so many things that are easy to implement when it comes to sleep that don't require venturing out into those waters and again we're not here to tell anyone about whether they should venture or not that's completely your choice all i'm saying is that if you want to think about optimizing your sleep there are a number of ways that you can do it that don't necessarily require you to swallow and i think or inject anything called you know smoke anything or right and for which the margins of safety are quite quite wide right that's that's the other one yes sorry so speaking of low-hanging fruit i don't know how low it hangs in reality but what what about kiwi they're delicious to me anyway yeah the humble kiwi fruit um named not um shouldn't be mistaken for the the the um flightless bird of uh new zealand which is the native bird that we're talking about the kiwi the fruit here which um those trees and shrubs are um mostly um south east asia kiwi fruits have been previously touted as potentially having a sleep benefit which again got me curious and i at first threw it out to my knowledge there's really only one published human study that's of any value but what they did find was that it decreased the speed of time with which it took you to fall asleep these are you ingesting the whole kiwi so it's ingesting the whole thing with the skin skin people cringe when they see me well i don't eat this no no no i think the idea is some of the good stuff and i'll come on to this may actually be in the skin it's one health thank you you just you i just want you just help me win a bet i'll give you your okay okay yeah you can familiarize by the way this skin is used no no he just told me to say that so he went no he did not um so the skin seems to be part of this potential sleep equation and that's the d yeah they um you fell asleep faster and you stayed asleep for longer and you spent less time awake throughout the night and i just thought well you know that's one study what can you really do with that there is another study however in an animal model which is you know a little bit more interesting and once again they found a very similar phenotype that the rats oh sorry they were mice the mice fell asleep faster and they also spent longer time in sleep the sleep duration also increased what was also interesting mechanistically and this is not the mechanism that i think ties together tart cherries kiwi fruit and you know things like melatonin because i think there could be one common binding mechanism what they found in the animal study is that they could block those kiwi fruit sleep benefits using a gaba blocking agent now gaba gaba which stands for gamma amino butyric acid is one of the major inhibitory neurotransmitters of the brain it's kind of like there's actually occurring sedative right sort of yeah it's the kind of the red light on the traffic light signal you know um others are green light um gaba is red light so by playing around with some sort of clever drugs to manipulate the system they could prevent the benefit of the kiwi fruit by sort of buggering around with the gaba receptor meaning that perhaps part of the kiwi fruit benefit on sleep was mediated by the brain's natural inhibitory neurotransmitter system called the gaba system and i thought that was that was kind of in that convinced me a little bit more that maybe there's something here to read into so to be determined again here is the banner but it you know tart cherries and kiwi fruits the data surprised me because in part i was so preoccupied with being you know i don't know a bit pureish about in a bit snobby thinking though come on that's definitely not going to work well i look forward to a day when supplements are no longer called supplements because at the end of the day whether or not something has an effect whether or not it's a whole kiwi fruit or a derivative of kiwi fruit will depend on the molecular compound and as you mentioned this potential mechanism via the gaba system um that's like we both as scientists get excited about mechanism because when you can trace a mechanism in a pathway it provides a rationale a grounding for why kiwi of all things or tart cherry of all things might help increase total sleep time uh i'd be remiss if i didn't mention or ask about tryptophan and serotonin i can totally say when i've taken tryptophan the precursor to serotonin or serotonin itself i have a horrendous night's sleep i fall asleep very easily and i experience ridiculously vivid dreams neither pleasant nor unpleasant is kind of a mishmash and then i wake up and i experience several days of insomnia that and i've done the the positive control and the negative control and all the variations thereof to confirm that at least for me supplementing with serotonergic agents is a bad idea for me and um tryptophan is a common sleep supplement and sleep aid that's discussed the normal architecture of sleep involves the release of serotonin but in a very timed and regulated way what are your thoughts about serotonin in sleep if you had to kind of put that into a nutshell and then why supplementing sup with serotonin and or its precursor tryptophan might be a good or a bad idea for somebody i think one of the potential dangers is that based on what's going on in your body that can change the absorption of natural sort of tryptophan and serotonin uptake within the brain itself so i'm always thoughtful when you're playing around with that mother nature dynamic as it were the data as you described is a little bit all over the map some people say that it knocks them out other people say just like you do it has a terrible impact on my sleep and when i stop it it's pretty bad for a couple of days it seems to have this lingering after effect i think what could be happening here is we need serotonin to just as you described be modulated in very specific ways during the different stages of sleep if you look at the firing of the brain epicenters where serotonin is released and there's a bunch of them in the brain stem what you find on the release of of serotonin 2 when we're awake it's usually in high concentrations as we start to drift off to sleep it lowers some but not necessarily dramatically as we're going into non-rem sleep but then when we go into rem sleep serotonin is shut off the other one of the other neuromodulators noradrenaline also shut off rem sleep is the only time during the 24 hour period where we see noradrenaline and serotonin or norepinephrine completely shut down when i say serotonin we're also talking 5-htp sorry 5-ht that's just its chemical name here so whether it speaking about serotonin 5ht it's the same thing norepinephrine noradrenaline both of those need to be shut down for you to produce rem sleep the other one of the other neuromodulators that then ramps up to produce rem sleep is acetylcholine so these three neuromodulators have this incredible reciprocal dance that they have for you to generate what is called a natural architecture of sleep throughout the night it's the push-pull again it's a push pull again you know it's you know it's chest and back it's you know whatever you want to think of that's why i think if you're trying to increase dramatically drive up your serotonin levels at night and that sustains throughout the night when you're trying to get into rem sleep you could be artificially fragmenting rem sleep now i don't know the data i don't think anyone's really got no good data but that's why i would be you know if you were to say matt two years time that's the data help me understand the potential mechanism or let's design some experiments where would you go first i would say let's look at the disruption of rem sleep non-rem sleep reciprocal regulation because you know you need serotonin to be you know up at one time down at another so i i um agree with everything you said and i'm um i'm personally never taking tryptophan or serotonin again unless there's some clinical reason for that uh that i would need to do that i want to ask about some other pro-sleep behaviors but before i do that let's talk about naps i love naps i come from a long history of nappers uh my dad always took a nap in the afternoon i take a 20 or 30 minute nap or i do a practice which i um took the liberty of coining nsdr non-sleep depressed some sort of just passive laying out their feet up elevated sometimes people do you or i'll do yoga nidra i'll do hypnosis or something of that sort but 20 or 30 minutes of that has been very beneficial for me to get up from that nap or period of minimal wakefulness we'll call it and go about my day quite well and also fall asleep just fine what are the data on naps uh do you nap and what are your thoughts about keeping nap short meaning 20 to 30 minutes versus getting out past 90 minutes two hours so uh for you personally naps yay nay or meh i don't nap um and i've just never been a habitual nappa is that because you don't feel sleepy in the afternoon or because we don't feel sleepy you're just heartier than i am i wouldn't say hardier i may be um less capable of falling asleep um but nicely dry afternoon no no i don't drag through so you don't nap because you don't feel a need to nap that's right yep now it's not that i am immune to what we call a postprandial dip in alertness i definitely feel as though there can be this kind of ethanol afternoon lull where you know i'm not quite as on as i was at 11 o'clock in the morning and we know the physiology to that which brings us back to whether we were designed to nap so for naps we've done lots of different studies and other colleagues have done these studies too naps can have some really great benefits we found benefits for cardiovascular health blood pressure for example we found benefits for levels of cortisol we found benefits for learning in memory and also emotional regulation how long are the naps typically in those studies anywhere between 20 minutes to 90 minutes sometimes we like to use a 90 minute window so that the participant can have a full cycle of sleep and therefore they get both non-rem and rem sleep within that time period then when we wake them up we usually wait a period of time to get them past what we call sleep inertia which is that kind of window of grogginess where you say to your better half look you know darling please don't speak to me for the first hour after i've done anything right now after the first hour of waking up you know i'm not just i'm just not the best version of myself so we wait for that time period and then we do some testing and we've done some testing before and after and we look at the change and that's how we measure what was the benefit of naps and the reason why we sometimes do 90 minutes so that they get all of those stages of sleep and then we correlate how much benefit did you get from the nap and how much of that benefit was explained by what rem sleep you got what deep sleep you got what light sleep you got so that's the only reason that we use that as an experimental tool what we've also found is that naps of as little as 17 minutes can have some quite potent effects on for example learning none of this is novel nasa pioneered this back in the 1990s and during the missions they were experimenting with naps for their astronauts and what they found was that naps of little as 26 minutes improved um mission performance by 34 and improved daytime alertness by 50 percent and it birthed what was then called the nasa nap culture throughout all terrestrial nasa staff during that time period so it's long been known that naps can have a benefit naps however can have a double-edged sword there is a dark side to naps and it comes back to our story of adenosine and sleep pressure the longer we're awake the more of that sleep pressure adenosine that we build up but what i didn't tell you is that when we sleep the brain gets the chance to essentially clear out that adenosine and after about 16 hours of wakefulness and then after about eight hours of sleep eight hours of sleep seems to be able to allow the brain to decrease its adenosine levels back to normal and so naturally we should start to wake up which also aligns with your circadian rhythm and those are two separate processes but with about eight hours of good quality sleep seven to nine hours for the average adult we are free of all of that adenosine we've evacuated it essentially out of the brain and we wake up naturally feeling refreshed the reason that naps can be potentially dangerous is that when you nap you are essentially opening the valve on the pressure cooker of sleep pressure and some of that sleepiness is lost by way of the nap so for some people and not all people and you're a great example of this some people however if they are struggling with sleep at night and they nap during the day it makes their sleep problems even worse so for people with insomnia we typically advise against napping and the advice is if you can nap regularly and you don't struggle with sleep at night then naps are just fine but if you do struggle with sleep stay away from naps if you are going to nap try to limit your naps try to cut them off a bit like sort of caffeine maybe you know eight to sort of 12 hours maybe not that you know far off maybe sort of seven to six hours is a good rule of thumb try not to nap essentially late in the afternoon and if you do take a nap and you want to maintain your you don't want to have that grogginess hangover that can happen after a full night of sleep for the first hour try to limit it to about 20 25 minutes and that way you don't go down into the very deepest stages of sleep which i if i wrench you out of with an alarm then you just kind of feel you almost feel worse for the first hour after the nap i've definitely experienced that if i over sleep certainly if uh the sun goes down during my nap and i wake up and light overall lighting conditions have changed i find it very hard to jolt myself back into the evening and it can screw me up so i try and keep those naps pretty brief and i should say um i i'm very happy to hear you mention individual differences and why some people might want a nap and other people might not want to nap uh i have a colleague leech and low he'll be familiar to many neurobiologists who's a absolutely spectacular scientist um member of the national academy howard hughes investigator just a phenom and uh has a ton of energy but years ago i learned that he always takes a nap in the afternoon so much so that when he travels to give seminars at other universities he will tell his post lunch um host whoever it is that he's supposed to meet with may i have your office for 30 minutes of our sometimes 30-minute discussion or 60-minute discussion because i like to take a nap and he does that and then gives his his talks are typically in the afternoon in academic culture and he describes the the effect of the nap for him the short naps in the afternoon being so profound for his productivity that's actually what inspired me to start feeling okay about my desire to nap yeah and so i think uh for me that was great vindication for those that might feel guilty about wanting a nap but i i take to heart your note about um avoiding naps if you have trouble falling and staying asleep because i think that they i know i have family members who also if they nap they're a wreck they can't sleep yeah i think it's just we've often been very pro sleep we as the sort of the sleep community so i think it's good to always point out these potential dark sides of of any aspect but you're absolutely right no one should feel guilty about getting the sleep that they need and i think that's been one of the big problems in society society has stigmatized sleep with these labels of being slothful or lazy and we're almost embarrassed you know to tell colleagues that we we take a nap i think sleep is a right of human beings and i therefore think that sleep is a civil right of all human beings and no one should make you feel unproud of getting the sleep that you need no i i love that and i it's an important point um i also feel that one of the best ways to um beat your competition in any endeavor is to outlive them so and now that we know that sleep can enhance uh longevity and lack of sleep can shorten one's life um that's all the justification i need anyway can somebody sleep too much is it possible to get too much sleep it's a very good question and there are probably two things to say about it there is a condition that we call hypersomnia but that's a mixture of things it's where people have either a very high sleep need or they are very sleepy during the day and they're typically falling asleep and these can happen in a variety of different clinical contexts one of the places where we've often seen hypersomnia believed to manifest is in depression but if you look at some of those studies it turns out it looks more as though those people are simply reporting being in bed longer but not necessarily sleeping longer and that fits very well with one of the profiles that we know of depression which is anadonia you don't get pleasure from normally pleasurable things so you just don't want to go out into the world you don't want to interact because you're depressed so what do you do you just stay in bed blind clothes watching tv right and that just looks as though you know when people say what time did you go to bed and what time did you get out of bed the mistake made in that question is okay that's how much time they're sleeping when you should have said what time did you fall asleep and what time did you wake up and the answer could be very different so that's hyposomnia from a clinical context can you sleep too much though one of the data points that argues yes that's possible is when we look at all-cause mortality certainly what you find is that using the sweet spot of seven to nine hours when you start to drop below seven hours there is a relationship which suggests that the shorter your sleep the shorter your life short sleep in that regard predicts all cause mortality but it's again not a linear relationship like the one that we've seen with rem sleep once you get past nine hours the mortality curve stops going down and then once you get further 10 11 hours it hooks back up again it's almost like a j shape tilted over a little bit and reversed so there's this strange hook what's going on here right now sleep science has at least two non-mutually exclusive explanations for this the first is that if you look at some of those populations the idea is that the whatever was causing them illness and took their lives was just too much for sleep to deal with however we know that when we get sick one of the things that we do immediately in this whole mechanism an inflammatory mechanism cytokine mediated when we get sick we want to sleep more we just want to kill up in bed and you know sleep it sleep it off so the argument there is that it's not that sleep was killing people prematurely it was that these people were calling on this the help of sleep they were calling on this thing called the swiss army knife of health that is sleep but whatever it is that they were facing was just too powerful for sleep to overcome so it artificially looks as though more sleep leads to a higher risk of death when sleep was actually responding to the mortality risk and it lost the battle that's one argument the second is that we know that sleep quality and poor sleep efficiency is a very strong predictor of all-cause mortality and when you look at people who often report sleeping long amounts 10 or 11 hours they typically report having very poor quality sleep so because their quality of sleep is poor they just try to sleep longer to try and get some of that back so again here now it's poor quality sleep masking as too much sleep leading to this artificial huck which looks like mortality that's a second explanation a third which is more of a duncan which is just kind of like a thought experiment and i'm of this mentality i don't know how many other people share this i actually think there could be a thing as too much sleep physiologically i think it's possible but the reason i think that is because it's no different than food water or oxygen can you overeat yes you can can you under eat of course light in the early part of the day throughout the day wonderful light late in the day right at night detrimental bi-directional you know for water can you over hydrate hyper neutrino it can lead you know it happened in the 1990s and 2000 with the ecstasy craze where governments were saying you're dehydrating you're dancing all night please drink water and they drank too much water their blood electrolytes went you know all over the place and they were having cardiac arrests or stroke yeah people were dying and they were dying because of excessive hydration can you get too much oxygen hyperoxemia and it can cause free radical damage which can be profoundly harmful and kill brain cells can you sleep too much you know which is the fifth element of the life equation you know alongside you know food water oxygen um you know so forth i should say you can't even count clearly i'm sleeping well um yes i think there could be that possibility are most people in danger of getting too much sleep oh contra if you look at the data right so yeah but i i don't dismiss that idea i think it's it's possible it's that's a very thorough and very nuanced and yeah very clear answer so i i um it's so interesting to think that a lot of the the data that out there that talking about being in bed too long that it's just trying to compensate for the actual fragmentation of sleep so what i'm coming away with is that there are many paths to this and uh both positive and things to avoid but the idea is to get most nights a similar amount probably seven to nine hours somewhere in there of high quality sleep that this notion of sleep quality is going to become i would hope uh a phrase that more people think about and learn about and cultivate as a practice i want to ask about a set of behaviors that i'm at least i'm aware of at least one company is starting to track in their sleep monitoring device and that's um orgasm and sex orgasm and masturbation topics that are you know are somewhat um sensitive um but from the perspective of biology right none of us would be here we're not for uh sperm meats egg in some fashion either in a dish or or in vivo um but what what are the data as as you know them to be or maybe your labs even doing this kind of um work and exploration about the role that sex orgasm masturbation play in getting to sleep and staying asleep and sleep quality certainly those behaviors and those physiological events have been part of our evolutionary history right um what's the story there what can we say about this in in terms of um science and and dare i say practice yeah i mean it's almost that caricature of you know in the movies where you know a couple makes love and then all of a sudden you just sort of hear snoring or you know it happens with the idea that it's somewhat somnogenic that it's sleep promoting well the orgasmic increase in prolactin well that's is is is interesting ought to be a set a naturally occurring sedative that presumably has a function in and oxytocin has that also that benefit where you see you know a dissipation of the fight or flight branch of the nervous system which has to happen for you to fall asleep that's why we often see you know here at the sleep center we'll see a phenomenon called wired and tired where people say look i am so desperately tired i am i just i'm so so tired but i can't fall asleep because i'm too wired so your sleep drive you're you're desperately tired it's there but because you're wired because you've got too much sympathetic activation too much cortisol as well you can't fall asleep it's a it's an impressive roadblock to anything like good sleep and it's one of the principal mechanisms that we now believe stress and physiological activation that is the underlying cause of many forms of insomnia but coming back to sex the data is actually quite compelling that both either subjectively assessed sleep quality or objective amount of sleep sex that has resulted in orgasm and i think it's that latter part that typically needs to happen i would imagine so um that you know so between two mutually exclusive uh individuals um were both are you know beneficial in terms of receiving an orgasm yeah i would say any discussion about sex we were referring to consensual age age-appropriate species appropriate context approach wow i would never have even gone by the species in there because it's the internet and people will come up with all sorts of ideas so i i think that age-appropriate i think age-appropriate consensual context appropriate and species appropriate covers all the bases but if i missed any put them in the comment section and we'll be sure to take note yeah no i think that's uh that's really well said um and important to say so the data is the when you look at couples who have orgasm we've also however found benefits of masturbation and it's not frequently spoken about but what it if you do some surveys it turns out that people will often use masturbation as a sleep tool if they're struggling with sleep and i know this sort of sounds almost like a strange conversation or it's a taboo conversation but i i think we just need to be very open about i started off in science um one of the things i worked on uh early in my career not the very first topic was uh the topic of early influences of hormones estrogen and testosterone on sexual development of the brain and body and when you are weaned in a laboratory like that regardless of what era you look at sex and its behaviors and its hormones and its physiologies as a scientist and so i think that's to be clear what we're doing here we're exploring these um these behaviors from that from that perspective i mean one thing is for certain everyone is here because a sperm met an egg either in a dish or in vivo as we said before and um at least in 2021 there's there's no way around that fact yeah um and what preceded that is typically this act we call sex and sometimes hopefully uh i like to think uh orgasm is associated with that sexual activity masturbation as one dimension of that is something that i think it can and should be discussed if in fact there are data that relate it to sleep yeah and both of those roots seem to lead to a sleep benefit now i'm not saying that it's all about the orgasm i think as we spoke about with oxytocin there is some degree of per bonding that if you have a partner and you experience you know an intimate loving you know relationship that involves that then you can have hormonal benefits that are sleep promoting that may not necessarily be seen if you're just engaging you know in the solo singular act of masturbation so what we certainly know and i i am not someone to take any advice on when it comes to and i think relationship wise or sex wise that's a different episode yeah certainly and that's not a podcast series that i'm going to be releasing anytime soon it's going to be mostly about uh sleep although i will touch on i'll release a podcast on sleep and sex but that's the data that we have so far we also know that it works both ways though and it's commonly this the same way with sleep um you know sleep and exercise sleep and diet how you eat can affect how you sleep how you sleep can affect how you eat same with exercise and it turns out it's the same way with sexual behavior too so here we're talking about whether sex can help with sleep can sleep help with your relationship and sex and the answer is yes it can firstly we know and we've spoken a little bit about this that the reproductive hormones are under profound sleep regulation both estrogen and testosterone testosterone because we hear so often as well but women who or i should say anyone who's interested in having higher levels of estrogen or normal healthy levels of estrogen i presume the data show for estrogen what the data also show similarly for testosterone which is if you get too little or poor quality of sleep both sex steroid hormones as they're referred to testosterone and estrogen which are present in both males and females and every variation thereof are going to be diminished below normal healthy estrogen testosterone um fsh in women uh a key hormone in the regulation um for um kefir conception of course all of these sex hormones seem to become significantly disrupted when sleep becomes of short quantity or poor quality we also know that in women sleep disruption can usually lead to menstrual cycle disruption we know this particularly from evidence in shift-working women where they are nighttime shift workers they struggle with sleep during the day often menstruation is disrupted or even becomes impaired but we also know it works this way not just for sex hormones but for sex itself for example we found that for every one hour of sleep extra sleep that a woman gets her interest in becoming sexually intimate with her partner increases by 14 which is you know a non-trivial amount and then the final part of i think this equation when it comes to sleep and sex is your your relationship itself and there's some great work here from uc berkeley by um professor serena chen and what she found was that restless knights mean for far more brutal fights in your relationship and they did this in vice numbers of different elegant ways and vice versa as well i mean not that i've ever had conflict in relationships like you know i just this is just data i've read i've never experienced that at all um so and they found reliably that sleep would predict higher likelihood of relationship conflict secondly if you got into that conflict the chances of you resolving it were significantly lower when the parties had not been sleeping well part of the reason is because when you are not well slept your empathy goes down so you're not you're taking more of an abrasive stance with your partner rather than a more agreeable stance with your partner so at almost every dimension of a human loving relationship sleep can have a dramatic impact i think these are really important things to underscore one of the most common questions i get because there seems to be a community of people on the internet that are obsessed with this um i don't know who they are because it's all all this internet stuff is shouting into a tunnel and getting comments back and written form it's a very bizarre conversation so to speak um is whether or not sexual behavior itself lowers or increases testosterone and i went into the data um which spans many decades actually both animal studies and human studies and it seems just to underscore this as long as we're talking about the subject that it does seem that sexual activity sex be between two people does seem to increase testosterone in both there is this question about orgasm or no orgasm ejaculation no ejaculation and and indeed there do seem to be some effects of of um of restricting ejaculation in males as a form of further increasing testosterone so sex without ejaculation further increasing testosterone but the data are not clean okay um presumably because organizing these sorts of studies and getting truth in in self-reporting is probably hard to get from from subjects but um but it everything sort of points in the direction that provided that the relationship is a healthy one it's it's consensual it's age appropriate context appropriate species appropriate that sex between two individuals does seem to increase the sex droid hormones testosterone and estrogen toward healthy ranges and what i'm hearing now the sort of gestalt of the discussion we just had is that that too can promote sleepiness restful states and quality sleep and um i think this is an important conversation that just hasn't been held enough i mean sooner or later um both in the u.s and elsewhere we're going to have to acknowledge that we are biological organisms of some sort and that we have choice in life about all these things um from supplementation to sex or no sex etc but that they have profound effects on our core biology i mean it's fascinating to me that the areas of the hypothalamus the pre-optic area the super-optic areas those areas which the names might not mean anything to anybody besides matt and i sitting here but those areas sit cheek to jowl with each other in the hypothalamus and control sleep and sex yeah the trigger of orgasm the appetite for food yeah the appetite for water for electrolytes i mean the hypothalamus is kind of a um a festival of of neurons with different booths for different uh such as a small structure in the brain but it's the orchestrator of a vast number of our behaviors disproportionate in terms of its size versus effect yeah i don't think you can go to this hypothalamic festival without uh at least seeing all the booths whether or not you decide to visit them or not um master analogy so um so i i'm so i'm glad that we've broached that conversation and i hope people will um will think that we've approached it with the appropriate level of sensitivity it's an important one that we're going to hear more about one way or the other people are certainly thinking about this if not engaging in in these sorts of behaviors or avoiding them um so the more we can understand about the biology the better and so thank you for bringing that topic up because for the record matt uh tabled it for discussion i said we were just like chatting outside and i think we said something about the sensitive section yeah we can go that's absolutely interesting absolutely um i want to touch on just two remaining topics one is are there any unconventional sleep tips or things about sleep that that we've overlooked if we've covered everything great but um you know we're here to keep the room cool we here uh because of this temperature phenomenon the light aspects the considerations about alcohol cbd marijuana um cognitive behavioral tart cherry fruit kiwis perhaps perhaps please don't put me on the hook for tot cherries i was just offering what i know about no and these are considerations and and whether or not people batch these things i i won't even list them off now because they're too many jokes that one one could make um and i have no affiliation with any of these products i'm going to take out stock in a kiwi company no i'm just kidding um but the question i have is about any unconventional or lesser-known things or maybe you do things or you think about things just in a purely uh exploratory way as a scientist of the you know the the what-if uh kind of things that you know what if it turns out that and i hear i just i i've got a blank there for you to fill in i think you know beyond the standard you know fur that i've dished out plenty of times of sleep hygiene of you know regularity temperature darkness um alcohol caffeine and we've we've spoken about all of those what are some more unconventional tips i guess the first one which is unconventional along the lines of naps if you've had a bad night of sleep let's say that you're starting to emerge with insomnia and you've had a bad night of sleep the advice and i learned this from my wonderful colleague michael perlis do nothing what i mean by that is don't wake up any later don't sleep in the following day to try and make up for it don't nap during the day don't consume extra caffeine to wake you up to try to get you through the day and don't go to bed any earlier to think that you're going to compensate and i can explain all of those things but if you wake up later you're not going to be sleepy until later the evening so you're going to go to bed at your normal time and you won't be sleeping you'll think well i just came off a bad night of sleep and now i still i'm i can't even get to sleep and it's my normal time it's because you slept in later than you would otherwise and you reduce the window of adenosine accumulation before your normal bedtime so don't go don't wake up any later don't use more caffeine for the reasons that are obvious because that's only going to crank you and keep you awake the following night or decrease the probability of a good following night of recovery sleep third um i mentioned don't take naps because once again that will just take you know naps particularly later in the afternoon i almost liken them to snacking before a main meal it just takes your appetite off the edge of that main meal of sleep so don't do it and then finally don't go to bed any earlier resist and resist and go to bed at your normal time what i want to try and do is prevent you from thinking i had such a bad night last night and i normally go to bed at 10 30. i'm just gonna get into bed at nine o'clock because last night was just so bad but that's not your natural bedtime and it's not aligned with your natural chrono type because presumably you kind of know something about that or a morning type evening time you're trying to sleep in harmony which is usually how you get best quality sleep but you go to bed at nine and my body is not ready to to sleep at nine o'clock but i'm worried because i had a bad night of sleep last night so i get into bed and now i'm tossing and turning for the first hour and a half because it's not my natural sleep window but i just thought it was a good idea and if i didn't know anything about sleep i would think all of these same things too so i'm not finger wagging but after if i have a bad night of sleep and i am not immune just because i know a little bit about sleep doesn't mean i don't have my bad nights i do doesn't mean i haven't had bouts of insomnia in my life i have but after a bad night of sleep i do nothing i don't do any of those four things i think the second tip i would offer in terms of unconventional is have a wind-down routine many of us think of sleep as if it's like a light switch that we just jump into bed and when we turn the light out sleep should arrive in that same way just the binary you know it's on or it's off sleep is a physiological process it's much more like landing a plane it takes time to gradually descend down onto the terra firma of what we call good solid sleep at night find out whatever works for you and it could be light stretching i usually meditate for about 10 or 15 minutes uh before bed some people like reading try not to watch television in bed that's usually advised too much too much light too activating you know you can listen to a relaxing podcast although we can speak about technology in the bedroom too but have some kind of a wind down routine it's you know it's almost like you know you wouldn't race into your garage and come to a screeching halt from 60 miles an hour you typically down shift your gears and you slow down as you come into the carriage this is the same thing with with sleep too so that's the second thing have some kind of a wind-down routine find what works for you maybe it's taking a hot bath or a warm shower and then stick to it just we do this with kids all the time we find out what their bedroom sorry their bedtime regiment is and then we just stick to it faithfully because but we humans are the same way too the third thing is a myth don't count sheep there's a study done here at uc berkeley i didn't do this today i wish i did it was by my colleague professor allison harvey and they found that counting sheep actually made it harder to fall asleep it made matters worse as a con sorry counter measure to that what they did find was that taking yourself on some kind of a mental walk so think about a nice walk that you take in nature or walk on the beach or even a walk around an urban environment and visualizing that that seemed to be beneficial the other thing about um sort of that idea of shifting focus away from your mind itself get your mind off itself is a good piece of advice catharsis you can try to write down all of the concerns that you have and do this not right before bed but usually an hour or two before bed some people call call it a worry journal and to me it's a little bit like closing down all of the emotional tabs on my browser because if i shut the computer down and all of those tabs are still open i'm going to come back in the morning the computer's red hot the fan's going because it didn't go to sleep because it couldn't because there were too many tabs active and open i think it's the same way with sleep as well so try to think about doing that so just vomit out all of your concerns on the page i like that because my 3 am waking is often associated with me writing down the list of things that i forgot to do that i need to do yeah and in in once i eventually wake up from the later night uh second half of the night's sleep that stuff seems much more tractable and reasonable but uh it sure would be great to get that stuff out of the way before sleep well there's also something that i don't think people have spoken about a lot and i'd like to research it which is difficulty and anxiety at night in the dark is not the same difficulty and anxiety in the light of day and when we have those thoughts at night it comes with a magnitude of rumination and catastrophization that is disproportionate to that which you would describe when you are awake and i don't know what's going on about the brain and thought and emotion at the time i've got a bunch of theories as to why and that's why i like the idea of closing up zipping up all of those different components just get them out on the page and it feel and i at first thought this just sounds like hui it sounds very berkely it's kind of come by our we all hold hands and you know walk home at the end of the day but then this the data started coming out really good studies from good people and they found that keeping one of those journals decreased the time it takes you to fall asleep by fifty percent five zero amazing that's well on par with any pharmaceutical agent oh absolutely yeah i i'm convinced that well i've long thought that the worries and concerns and ideas i have at 3 4 a.m i've learned to not place any stock in them yeah because ever something i'm glad that you might um decide to eventually look at this in your laboratory because i feel like something is melted away or altered i suspect it's in the uh the regulation of the autonomic nervous system that it makes sense why a concern at 3 4 a.m ought to evoke more of a panic sense than a concern sentence and certainly that's my experience although not i'm fortunate to not suffer from full-blown panic attacks but everything seems worse at 3 4 a.m provided you're awake and we we need to sort of look into that because you know if you look at suicide rates around the 24-hour clock face disproportionately higher rates in those middle sort of night hours so no now i don't know if that's causative or not but something you know it could just be that that's the time when we're mostly lonely and we're by ourselves and that's the reasons it's got nothing to do with sleep or the night time i don't know um so that's the third thing i think the fourth sort of little tip i would give that's unconventional is remove all clock faces from your bedroom including your phone including your phone and resist checking it now i know and i can speak about the phone too that genie of technology is out the bottle and it's not going back in any time soon so we've got to think of scientists and sleep scientists you know as to what we do with you know phones in the background years ago i was a counselor at a summer camp i worked with at-risk kids and the um there was a phrase that comes to mind here it's be a channel not a damn because when you try and damn certain kinds of behavior um physically damn certain kinds of behavior not morally damn um that too uh it just creeps over the edge and you get it and you get a a waterfall um so it has to be channeled the phone and devices have to be worked with and negotiated that's right and you know think about those mindfully too but clock faces remove all of those because if you are having you know a tough night knowing that it's 3 22 in the morning or it's 4 48 in the morning does not help you in the slightest and it's only going to make matters worse than better so try to remove all clock faces and i think that's one of those other tips that some people have found helpful but those would be sort of some slightly unconventional i guess more than your stock fare of here are the five tips for sleep hygiene tonight um so those are terrific sleep tips and um several of which if not all of which i'm going to incorporate um matt this has been an amazing uh deep dive on sleep and it's positive and negative regulators i hope it hasn't been too long and i i don't know this has been great cut it down shorten it to uh you know the five minutes of meaningful stuff that i offer absolutely not ever it is chock-a-block full of valuable takeaways it's been uh tremendously fun for me to uh dissect out this incredible aspect of our lives that we call sleep with a fellow scientist and a fellow public educator i want to say um several things first of all um we should say where people can find you although i it shouldn't be that difficult these days you're a very present on the on the internet um for better for worse i think it's wonderful that you're out there look it's a public health service that you're doing no one requires you or any other scientist to to get out and share this information my sense of you knowing you a bit and from following your work very closely with your scientific work in detail and um your public facing uh educational work is that you very much want the best for people and it's it's an interesting thing as a scientist or a clinician to know that the that certain answers exist that we don't have all the answers but that there is a better path there are better ways and people can benefit in a myriad of ways so um for that because i know that to be very genuine in you um you want the best for people and you're offering tremendous advice and and um considerations and people can take it or leave it that's the way i view it i also want to thank you for taking the time out of your day to uh to sit with me here and have this discussion it's a privilege it's a delight you know you and i um i think were like kind in lots of ways and i take you as a as a shining example of how you can effectively connect with the public and i know that we've had our conversations before we ever sat down sort of together about you know how to think about communicating with the public and the pros and cons of that and i've just loved your opinions i've been drinking it all in and then i think the third thing i'd like to say is thank you for being such an incredible sleep ambassador the series that you've released on sleep the way that you speak about sleep the way that you moderate and of champion sleep it is remarkable so thank you for just being you know a brother in arms uh in that way well we are and and thanks for those those words um 99 of what i discussed there was the work of you and your colleagues in the sleep field so proper acknowledgement but thank you where can people learn more about what you're doing currently and what's coming next you're on twitter uh i am on um twitter i typically tweet um as the sleep dipper man so it's it's no it's just sleep diploma sleep diplomats diplomat on twitter sleep diplomat.com website uh if you want to learn more about the science that we do here it's humansleepscience.com it's the center for human sleep science um you can pick up a copy of the book if you want it's called why we sleep if you're curious about sleep that's one path to take and it's is there another like someday in the in the future uh i think there may be yeah right i think many many millions of people will be very happy to hear that i think it's it's starting to take hold and then um as we discussed i am more than kicking around the idea of a short form podcast rather than a long form not long form because i don't have the mental capacity or the interviewing um just capability that someone like you has so it will probably just be monologue short form so if there is some interest i'll probably do that as well so those are the ways that people can find me but overall if you're interested in sleep just listen to andrew that's the best thing i can tell all right well now now we're batting back and forth the the uh vector of action so to speak but um i do hope you'll start a podcast however brief or lengthy these episodes uh turn out to be because i do believe that's a great venue to get information out into the world and um we don't just uh want to hear more from matt walker i speak for many people um we need to the work you're doing is both um influential but more importantly it is important work it it has the impact that's needed especially in this day and age where science and medicine public health and the issues of the world etc are really converging so i know i speak on behalf of a tremendous number of people and i just say thank you for doing the work you do and for being you and thanks for being a good friend likewise too um and by the way i just going to note that it was nice that the two of us both got the um johnny cash uh memo about how to dress today uh it seems as though we're both kind of uh we got that same memo which will mean nothing to people who are listening but if you're watching the video you'll probably see what i mean andrew thank you for taking this time thank you so much so much matt thank you for joining me for my discussion with dr matt walker please also check out his podcast the matt walker podcast a link to that podcast can be found in the show notes if you're enjoying this podcast please subscribe to us on youtube on youtube you can also leave us comments and suggestions for future episodes and guests in the comments section as well please subscribe to us on apple and on spotify and at apple you can leave us up to a five-star review you can also support us by checking out our patreon account that's patreon.com andrew huberman and there you can support us at any level that you like please also check out our sponsors mentioned at the beginning of this episode links to those sponsors can be found in the show notes during this episode and in many previous episodes we discussed supplements one issue in the supplement industry is that many supplements don't contain what's listed on the bottle we therefore have partnered with thorn that's t-h-o-r-n-e thorn supplements because thorn supplements have the highest levels of stringency in terms of the purity of the ingredients and precision with respect to what's listed on the bottle is actually what's contained in those supplement bottles if you'd like to see the supplements that i take for sleep and for other things you can go to thorn.com the letter u huberman and there you'll see all the supplements that i take and can get 20 off any of those supplements as well as any other supplements that thorn happens to make that's thorn t-h-o-r-n-e dot com slash the letter u huberman and last but certainly not least thank you for your interest in science [Music]