Dr. Matt Walker: How to Structure Your Sleep, Use Naps & Time Caffeine | Huberman Lab Guest Series

[Music] welcome to the hubman lab guest Series where I and an expert guest discuss science and science-based tools for everyday life I'm Andrew huberman and I'm a professor of neurobiology and Opthalmology at Stanford school of medicine today March the 3D episode in our sixth episode series all about sleep with expert guest Dr Matthew Walker during today's episode we discuss how to structure your sleep for optimal mental health physical health and performance we discuss monophasic sleep schedules which are the more typical sleep schedule where you go to sleep at night and then wake up in the

morning so sleeping in one bout as opposed to polyphasic sleep schedules which are when you sleep in two or more bouts either at night or perhaps a shorter bout of sleep at night and another bout of sleep during the day we also discuss naps including how to nap how long your nap should be whether or not naps are good or bad in particular whether or not they're good or bad for you it turns out this varies according to individual we also discuss how your needs for sleep and naps vary across the lifespan and we discuss

body position during sleep which might seem excessively detailed but it turns out that body position during sleep is critical for ensuring that the sleep you get is optimally restorative as with the first two episodes of this six episode series today's third episode is filled with both science that is the biology of sleep and napping and body position and how those relate to one another as well as practical tools that you can use to vastly improve your sleep before we begin I'd like to emphasize 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 betterhelp betterhelp offers Professional Therapy with a licensed therapist carried out online now I've been doing therapy for well over 30 years initially I had to do therapy against my will but of course I continued to do it voluntarily over time because I really believe that doing regular therapy with a quality therapist is

one of the best things that we can do for our mental health indeed for many people it's as beneficial as getting regular physical exercise the great thing about better help is that it makes it very easy to find a therapist that's optimal for your needs and I think it's fair to say that we can define a great therapist as somebody with whom you have excellent Rapport somebody with whom you can talk about a variety of different issues and who can provide you not just support but also insight and with better help they make it extremely

conven vent so that it's matched to your schedule and other aspects of your life if you'd like to try betterhelp you can go to betterhelp.com huberman to get 10% off your first month again that's betterhelp.com huberman today's episode is also brought To Us by element element is an electrolyte drink that has everything you need and nothing you don't that means plenty of the electrolytes magnesium potassium and sodium and no sugar as I mentioned before on this podcast I'm a big fan of salt now I want to be clear people who already consume a lot of

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to try element you can go to drink element spelled LM nt.com huberman to claim a free element sample pack with your purchase again that's drink element LM t.com today's episode is also brought To Us by waking up waking up is a meditation app that has hundreds of different meditations as well as scripts for Yoga Nidra and non-sleep deep rest or nsdr protocols by now there is an abundance of data showing that even short daily meditations can greatly improve our mood reduce anxiety improve our ability to focus and can improve our memory and while there are

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refreshed in fact the science around Yoga Nidra is really impressive showing that after a yoga needra session levels of dopamine in certain areas of the brain are enhanced by up to 60% which places the brain and body into a state of enhanced Readiness for mental work and for physical work another thing I really like about the waking up app is that it provides a 30-day introduction course so for those of you that have not meditated before or getting back to a meditation practice that's fantastic or if you're somebody who's already a skilled and regular meditator

waking up has more advanced meditations and yoga needer sessions for you as well if you'd like to try The Waking Up app you can go to waking up.com huberman and access a free 30-day trial again that's waking up.com huberman and now for my conversation with Dr Matthew Walker Dr Walker welcome back Dr huberman an absolute pleasure let's talk about the different types of sleep because I think most people think of sleep as just one thing most people sleep at night some people also nap a topic we'll also discuss today but turns out there are a

lot of different different types of sleep what are the different types of sleep and what do they do for us and um I guess everyone's probably wondering already I certainly am what types of sleep are we already engaging in meaning am I involved in or having multiple types of sleep each night this is a fascinating question and it comes back to something we've discussed in a previous episode the different stages of sleep and how they unfold we've described that fascinating stuff what you're already asking though is is an incredibly sort of subtle but relevant question

how should I be sleeping in terms of the phases of sleep should I have one phase should I have two phases of sleep or should I have many phases of sleep in some ways you can answer that question on the basis of the lifespan because how it is that we sleep in terms of those chunking sessions changes as we develop to be clear in nomenclature I'm saying monophasic basic polyphasic unpack that monophasic obviously just simply means a single phase monophasic when you say phase you mean one bout of sleep correct so that would be within

a 24-hour period you are having a single bout of sleep basic then means that within that 24-hour phase you are having two bouts of sleep and we'll speak about how those bouts are split up are they split up between two halves in the middle of the night or are they split up in terms of longer at night Siesta like nap in the afternoon and then we can speak about polyphasic sleep polyphasic sleep we in sleep science have been using for many years in the context of infancy because there as any new parents will know infants

do not just simply have a nice single bout of sleep they're up they're down they're up they're down and have many bouts of sleep within that 24-hour period and that's polyphasic sleep the other term or the other application of that term polyphasic sleep has been used more so in the sort of interesting biohacker movement and we can we'll come back to that perhaps later on so how do these different phases of sleep change across the lifespan well we've already said that when you're an infant and you're first born within the first year of life you

are incredibly poly phasic and you are probably going through wake sleep phases every 2 hours why do you do that why can't you just simply be born and sleep in a monophasic way it's for at least two reasons first an infant needs to feed every two hours so their energy needs and their food intake requirements dictate that you can't sleep for very long because you need to be awake to feed and then you go back to sleep Within probably the first six months things will start to to change a little bit but the second reason

that you are highly polyphasic when you are first born is because your super chiasmatic nucleus and in another episode we spoke about this Central master 24-hour clock that beats out your Cadian Rhythm the rise and the fall the wake and the sleep that has not yet developed it hasn't been glued into place into the brain this 24-hour clock so the infant seemingly knows nothing about when it's light or when it's dark outside that just awake or sleep awake a sleeve so that's the second reason energy feeding needs is the first and then an absence of

yet a fully developed 24-hour clock in the brain to beat out that beautiful dictated Rhythm by about age one that number of phases of sleep are starting to decrease but it's still highly polyphasic it's not not until you get to probably age two or three that now you're starting to see this consolidation of sleep what do I mean by that sleep is now happening more dominantly in the night phase of the 24-hour cycle and there a few abouts of sleep during the daytime then perhaps by the time you're in kindergarten you may be down to

just two sleeps so now we've switched from polyphasic sleep as infants to basic sleep as kindergarten could you describe that it was basic patterns I recall in kindergarten um having nap time in the afternoon yeah they put out these little mats and every every kid would just kind like roll up it's actually sounds really nice it's one you know wouldn't and we'll speak about how some adults do this too but almost every kindergarten system that I've inquired about around the world different nations they all have this nap time and Any teacher will tell you if

one of those children does not nap during that period of time they are the Loose Canon they are the live wire and in subsequent episodes we'll speak about exactly how sleep harnesses and improves our emotional and mental health and how it falls apart when we don't so that that's how it certainly is emerging biologically and that's how we as a society respect that and accommodate that and then probably by the age of starting school so sort of five or six now we're starting to see fully monophasic sleep children sleeping long bouts at night and then

being able to sustain wakefulness during the day at that point you have locked in your monophasic pattern and that will continue throughout adulthood and into old age with a few caveats that we'll speak about so that's how sleep sleep unfolds in the monophasic biphasic polyphasic sleep across the lifespan it doesn't quite tell you however how those different stages of sleep change across the lifespan so I've shown you the view of sleep across the lifespan through one lens of the microscope if we click down one lens and focus more deeply on the different stages of sleep

there we see a fascinating story in uo for the most part you are in a sleep likee State as a fetus once you get to a certain point of development in utero that sleep-like state seems to be more so something that looks like REM sleep now it's not fully fledged full fat REM sleep yet but it seems to be something very much like REM sleep I say this because in the first episode I told you as we go into REM sleep and we start to as adults dream the brain paralyzes the body so that the

mind can dream safely those kicks and those punches and those elbows that uh a mother will feel from the fetus seem to be during this dream state often and I don't want to shatter any illusions of you start singing or you're cing and you get these bumps and these elbows and these legs kicking and it's beautiful it is beautiful but it turns out that it's probably the REM sleep state but the muscle sort of paralysis has not yet developed so you're getting these electrical burst this frenetic activity of REM sleep that we described but you're

not getting any of the blockade of the motor output and so it expresses itself as these kicks and these bumps and then during the first six months of life and at that point in the first 6 months those infants are sleeping anywhere between 14 to 17 hours a day that's it's immense isn't it I mean it's right up there if you look across the across philogyny and you ask which is by the way a fascinating Topic at some point we should do a a separate podcast on sleep across different species because I know like me

you love you know the whole variety of sweet but you've got elephants who will sleep as little as 4 hours and then you've got the little brown bat who is the rock star of sleep and it will sleep sleep almost 17 to 18 hours a day it nudges out the sloth in that sense wow can I ask you a question about that little brown P yeah does it sleep hanging upside down does so it can't have sleep paralysis in its little claws so it it will it will not have that paralysis but it goes through

the stages of sleep very quickly and this happens with birds as well so birds that flock on a branch they will sleep and they sleep in some fascinating ways what some sometimes with one half of the brain sometimes with both halves but then you say well if I'm on a branch and there's this wonderful Force called gravity underneath me and I go into REM sleep and I have that muscle paralysis which they do how does that work well they only have very brief REM sleep periods that last just for a few seconds and then they

regain their muscle tone got it couldn't couldn't help but ask it's genius the Flora and the fauna I especially that the fauna um enchant me that much so I don't want to draw us off course but now we know that they they can that's why the bats don't fall that's why the birds Don't Fall correct um so when you are then as an infant sleeping 14 to 17 hours what's happening with those different stages of sleep non-rem and REM at that point we can't really Define and separate the different stages of non-r because it's not

yet fully formed but we have what looks like a REM sleep active State and a a deep non-rem sleep passive state almost 50% of the time that an infant a newborn is asleep is spent in REM sleep why do I say that with some kind of wonder in my voice because as adults we're perhaps down to maybe 20% of our time spent asleep is in REM sleep but 50% of the time when an infant is asleep they are in rem why would this be the case and across all species that have REM and non-rem the

time when we see REM sleep in highest volume amount is always after birth there is something special about REM sleep and its function during that early period and we now start to understand why when you are first born you are still going through a huge amount of brain maturation and the recipe for the day there unlike when we are teenagers is exploding the brain with synapses all of these connections throughout the brain what we've discovered is that REM sleep acts as an electrical fertilizer to stimulate the growth of these connections within the brain it's almost

as though you could think about an internet service provider with this huge new neighborhood and the first call of business is to go in and wire up each one of those homes with these Fiber Optic Cables that's what REM sleep is doing and if you start to deprive and these were studies gosh done many years ago by Howard rthor and others if you deprive animals of REM sleep you stunt the developmental growth of the brain and presumably the whole animal and the yeah as a consequence I mean if you look at its social behavior even

just that it's profoundly abnormal because you don't have that REM sleep developed brain I mention this not because there is any causal evidence but we have seen REM sleep deep impairments in certain developmental disorders such as autism as well as ADHD I don't think there is any supportive evidence yet to come out with a claim that part of the trajectory underlying those conditions is abnormalities of REM sleep but I it's a very active area of research so it's a fascinating time though during infancy when you get these huge amounts of REM sleep why because of

what we call synaptogenesis is which is simply the creation of sinapsis Genesis then as you move from 6 months across the next 18 months something odd happens Total Sleep time starts to decrease REM sleep starts to decrease but non-rem sleep actually increases even though Total Sleep time is decreasing and there's a strange peak in lighter stage nonrem what we call stage two nonr and those sleep spindles that I was describing in the first episode These bursts of electrical activity we will speak about the role of those sleep spindles in improving motor skill learning and we've

done a many many years of work in this area why is that relevant to this phase of life that's right around the time when infants start to coordinate their limbs in a skilled way and begin to walk and we believe that it is part of the process of the development of the motor system enabling walking to begin amazing so then things will change further sleep time continues to decrease and by about age five or six now the cocktail blend of nonrem and REM is down to a stable ratio that will remain throughout the lifespan which

is a 4:1 ratio so about 20% of the time that you're asleep will be REM sleep and the remaining time time will be 80% of that time will be non-rem sleeping provided one is getting sufficient total amounts of sleep correct and getting it at the right moments in time that we described in the first episode getting that sort of that appropriate chronotype match to the 24-hour clock that will certainly alter those things too so that's how sleep unfolds both at the first level of the lens monophasic basic polyphasic and then double clicking how the different

stages of sleep unfold and what the reasons are behind that I then said once we're adults we become monophasic yes to a degree but there is some contention about the way that we sleep in modernity that we may not be sleeping in the way that we were designed to sleep which brings us back to basic sleep in the first episode we spoke about this strange after afternoon dip in our alertness that happens called the postprandial dip and it happens somewhere between the 1 to 4:00 p.m. region and it's measurable and it seems to be biologically

wired into us if you look at certain cultures that are not touched by modernity so we and others have studied studied hunter gatherer tribes they don't quite sleep the way that we do and they don't sleep the way that we do for at least two reasons the first is that they will often have a siesta like pattern of behavior where especially in the hot dry season they will take a nap in the afternoon in the wet cooler season that may not be the case but they certainly have more of a basic pattern where they'll sleep

longer at night and then have a short nap Siesta like and then of course there are Latin and Mediterranean cultures and they have this practice of the Siesta like Behavior coming back to the hunter gather tribes the way that they also do not sleep in a similar manner to that which we do is the timing of sleep they don't go to sleep as the sun goes down they will usually on average as a group they will usually go to sleep about 2 hours after Sundown and then they will wake up not with the rising of

the sun they wake up just before that and you think how are they predictive of the light no the thing that changes first before the sun truly Rises is temperature and temperature is a very strong predictor that forces them awake so when you think about how they're sleeping then consider the term midnight most of us never really think about what the term means midnight refers to the fact that it is the middle of the night but for most of us in the modern world that's the time when we're thinking about sending our last email or

posting to social media midnight is no longer midnight for society but it is for them so should we be thinking about midnight as the middle of the night in the context of the uh extreme early person morning person who you know presumably likes to go to bed around 8:00 P.M wake up around 4:00 a.m. most people hear 4:00 a.m. and they go oh goodness you know that's early sort of um you know like the the mighty Joo willink is is uh famous for posting images of his of his uh digital watch usually I think it's

4:30 a.m. wake up and that's when he starts his workout so his Twitter and I guess they call X now feed and and Instagram is a replete with images of his watch 4:30 and people think goodness that's early right but he was a guest on this podcast spoken to him before but he goes to bed pretty early that's right most nights so in some sense you know midnight for him or for somebody with a similar schedule is truly middle of the night that's right right but for the other chronotypes for people that uh prefer to

go to sleep or who naturally um get sleepy around 10 or 11 p.m. or even later um how should they think about this biphasic polyphasic business because um at at some level um we all have to reconcile uh our sleep schedule with the with the demands of work and family and so on that's right so I was very specific when I said the hunter gather of tribes on average that's the way that they will sleep but like the rest of society there's a huge distribution and there will be some proportion of them who are a

little bit like Joo who will be on the early side of that on the very early side of that but then there are other people who are clear night owls and they may not be going to bed until you know 10: or 11: and waking up later so there is a distribution there you don't have to worry that my statement of midnight on average that does seem to be when we are dislocated from all of the trappings of modernity how a group of Representative humans on average will sleep but there is huge as I said

differences from one individual to the next by the way you can ask the question why do we have these things called chronotypes why is there such variability in how people have a preference for when they sleep wouldn't it just be easier if biology designed us all to be asleep at the same time not so we mentioned in the first episode that sleep is truly idiotic in the sense that you know you're not protecting yourself or the people that you care about and if everyone slept at the same moment in time you as a collective and

as an individual would be vulnerable for an 8 hour period 7 to n hour period but by way of this wonderful injection of variability as to preferences for when people sleep maybe there are some people who are going to bed at 8:00 p.m. and there are other people and they're waking up at 4: a.m. there are other people who go to bed at midnight and wake up at 8:00 a.m. so then think about that at some point what you've done is that there will always be someone or collection of people awake until midnight and then

will always be a collection of people who are awake starting at 4:00 a.m. so as an individual everyone gets their 8-hour opportunity but as a collective as a clan you are you've reduced your vulnerability down by 50% because Mother Nature injected the variability by way of genetics of chronotype to distribute that and lessen the burden does that make any sense it does and it reminds me of how the Circadian rhythm which we discussed in episode one is about 24 hours not exactly 24 hours the rhythm of the supermatic nucleus neurons that generate the Circadian rhythm

as I recall uh is rarely exactly 24 hours it's 24.2 or 24.4 and the idea in mind the just so story uh is that that variation allows for entrainment matching to the outside light dark cycle which changes across the year so you don't want it rigidly 24 hours because if there's any variation in light dark which of course there is you know even at the equator across the year there's subtle variations but certainly As you move away from the equator and so these these uh variations in you know your circadian rhythm uh clock scn supermatic

nucleus might be 24.2 mine might be 24.6 24 someone else 24.1 and in that sense um allows some uh malleability to to matching the Circadian rhythm to outside light dark rhythms is that is that a a decent parallel for what we're talking about it's a beautiful demonstration that there is always some it's almost wiggle room in how biology is programmed because some degree of sort of noise almost sarcastic noise can be very beneficial and it's much more predictive of the way in which the world works and it's much more adaptive for a species to enact

and to embrace that kind of variability and yours was a beautiful example that it's about 24 hours but it's certainly responsive to changes in light duration across the year and it has to be because we need to buckle ourselves to the light dark cycle for optimal survival and here is another demonstration of where it's not about the Cadian Rhythm but it's about the chronotype distribution not within an individual across the year but across individuals at any one moment in time and that variability once again provides a biological benefit in the first episode and again now

you're discussing chronotypes and one one thing that I've been meaning to ask is you said that chronotype is genetically determined but that necessarily mean it is directly inherited from Mom Andor dad meaning if your parents are both extreme early morning types will you grow up to be an extreme early morning type you already established that during infancy and development uh adolescence Etc that our chronotype is somewhat masked by some of the developmental uh um uh Necessities um but once we reach young adulthood and and our chronotype has been established uh can we look to our

parents to determine whether or not we are more likely to be in morning person or or late shifted it's very unlikely to find find anyone whose parents were both extreme morning types who is a neutral or an evening type and vice versa so my guess is that people with if they know of their biological parents and they know of their rhythms it's highly likely that you will at some point acquas in your lifetime to being very similar to them now there are certain life conditions and contexts where you can you know fight that um if

you're really into you know if you're someone who is in punk rock band and you're touring all the time even though your mom and dad may be morning types and you may be a morning type you're on the road you're playing gigs there's no chance but at some point let's say you retire and you give yourself the opportunity to express your natural Rhythm you will go back to that so yes it's highly genetic it's not enre highly genetic there is some degree of modification that happens on the basis of context and I've just given you

a good example of context and also your exposure to light you can be someone who is let's say a neutral like me but if you're constantly invaded by Electric Light at night you're drinking too much caffeine and you're on your laptop and your computer and your phone and you're always activated by social media it's very easy for someone like me to drift and become a 1 a.m. to you know 9 a.m. person that's not my natural type but context and the environment have shifted me but for the most part yes to your question I'd like

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I always answer ag1 if you'd like to try ag1 you can go to drink a1.com huberman to claim a special offer you'll get five free travel packs plus a year supply of vitamin D3 K2 again that's drink a1.com huberman okay so getting back to these different uh phase opportunities for Sleep uh clearly I'm getting the language wrong here but vacular monophasic basic and polyphasic um could you give us a few more examples of different types of biphasic and polyphasic sleep so coming back to basic sleep I describe one version once we are adults which is

the Siesta like notion one long bout at night short bout during the day and that bout during the day is usually matching that drop in alertness that we described it sort of hits that sweet spot right there and it's quite easy for some people to fall asleep in a period between somewhere between one and four 1 to four yeah and I know it's a large window but that just allows us to sort of know okay if you're someone like yourself who's a morning type you would probably start to want to nap a little bit earli

or if you were basic someone like me a neutral probably an hour and a half two hours later still but there is a different version of basic sleep for adults that has been described in the literature and it's fascinating but I don't think it's biological it's the notion that some people will have heard called first sleep second sleep and now you are splitting your sleep into two phases but they're split across the night so the idea is that you fall asleep and you'll maybe have 4ish hours and then you wake up and you then are

awake for several hours and then you go back to sleep for another 3 or 4 hours if you look in history and the the record of of human history it's very clear that there were some cultures doing this particularly if you look at some of the European cultures Great Britain in particular there is good evidence that somewhere between about the 15th to 19th century seems to have ended during the kind of dezian era people were describing this behavior and they would wake up in the middle of the night after about 4 hours they would make

food they would play music they would write they would make love it was a real thing and I'm not suggesting that it did not happen it clearly did and there's a there a great book that outlines this but is it the way that we were designed to sleep bif phasically versus the Siesta like and I don't think it is there is no good collection of evidence if you look at the biology of our human rhythms that argues that there is this magical period of a huge spike in Arcadian Rhythm that happens right in the middle

of the night that should force us awake there is one paper that's often cited for this and in truth that paper if you read it says nothing about first sleep second sleep doesn't speak about basic sleep at all and that paper I think is unfairly used as a justification of first sleep and second sleep and the paper to me has at least three problem it's a great paper there's no no problem with the paper and its hypothesis but its use as justification for first sleep second sleep has three problems the first is the artificial nature

of the study they weren't designing it to test the hypothesis but they had individuals in bed for 14 hours relative to a standard 8 hour period and sure enough what they found was that when you force people night after night to be in bed for 14 hours somewhere after about 6 or 7 hours they wake up and then you can't get out of bed in the study so you just lie awake and then at some point I don't know if it's through boredom or you drift back off into sleep and that was argued as a

clear demonstration of this split sleep but as I said they're awake usually for about six and a half seven hours also there was no magical Awakening period it's a probability distribution and what that means is if you look at the data it's just more likely that people will wake up after about 6 or seven hours and they're more likely that they will go back down into sleep it wasn't as though the whole experiment demonstrated a very clear termination of sleep that everyone had at that moment in time so that's the first issue um and the

second issue which is first issue it's kind of an abnormal thing 14 hours forced in bed the second is it wasn't a clear separation it's just simply higher probability the final issue is that it was a study done in only seven individuals healthy males and so I have yet to see it you know scaled up did it happen first sleep second sleep yes it did is there any strong evidence that that's how we naturally were designed and have evolved to sleep I in truth I don't think so at least I don't see good evidence right

now supporting that but remain open to it in episode one we talked a little bit about body position during sleep uh and how different uh degrees of uh incline or decline might impact uh some of the features of sleep and I can't help but ask now as you uh described this basic pattern for people that were essentially experimentally restricted to to the bed um is there something about being horizontal that makes us sleepy there is and it's perhaps not for the reasons that you would think which is okay I'm just pre-programmed when I lie down

and my head hits the pillow it turns out that it seems to be temperature that when your body is recumbent lying flat horizontal the distribution of how your body is able to move blood around the different regions and decrease your core body temperature meaning it can push blood warm blood out of the core of your body to these surface areas and when you push it out to the surface areas you release that heat it's this huge thermal dissipation that happens when we move Blood Out Of The Core to the surface you emit that heat and

your core body temperature plummets when your body temperature your core body temperature decreases you have a higher likelihood of sleepiness in fact it's very difficult for you to fall asleep if your core body temperature does not drop and by lying down the body's what we call vasoactive ability to distribute that blood in a way that is permissive for thermal dissipation of core body temperature is superior and that's the reason why we find it easier to fall asleep lying down than let's say semi-recumbent or certainly propped all the way up and it's probably the reason naturally

we evolve just to lie down on the floor very interesting maybe now is a good time to talk about basic sleep in the context of a about of sleep at night and the afternoon nap you've mentioned this postp parial dip that most people experience between 1: and 400 p.m. that many people try and combat with caffeine we will also talk about Caffe uh this episode um such an interesting substance and I think the most commonly used drug it is a drug after all worldwide I think more than 90% of adults worldwide consume caffeine on a

daily basis that's correct and I believe it is after oil it may be perhaps the second or at least the third most traded commodity on this planet and it is what we call a psychoactive stimulant is a stimulant and it's probably one of the only stimulants that we will readily give to our children and you know not be too concerned about it we'll get to caffeine in depth uh a little bit later in this episode but I can't help but uh just mention that someone I think it was Michael Polland said that you know caffeine

is one of the few drugs that almost everybody takes just to quote unquote feel normal yeah exactly you know it's sort of I think sometimes you know sleep deprivation is is simply just the absence of of caffeine and um so it's a very interesting chemical which I have in truth changed my mind on and I'm happy to speak about why I've changed my mind but also some God rails too well we'll we'll go there meanwhile I'll take a sip of my uh Triple Espresso here as we discuss as we discuss naps are naps good for

us should we nap what if we don't like naps why do we wake up from naps groggy sometimes and other times we feel refreshed tell us about napping naps are both good and bad depending on the situation naps can be a double-edged sword in other words we and others have done lots of studies on naps and the benefits are fascinating and St I'll tell you about one study we did we had participants assigned to one of two groups and at midday they all learned a whole list of new facts so it was a study about

learning in memory and then one group took a 90-minute sleep opportunity sort of focused right around that drop in alertness the other just remained awake lying on a bed and they just watched a nature documentary and then 5 hours later we had them do another learning session and so they've woken up after the 90-minute nap they've got through that sort of initial lull that we'll discuss what that is after you wake up everyone's now back to operating temperature so in other words I've had you try to cram in a whole list of facts at midday

and then a whole list of facts new facts again at 5 p.m. and I can ask what is the learning capacity of your brain at midday and at 5:00 p.m. and is there any difference in your learning ability when you have had a nap in between versus not and sure enough what happened in the group that did not nap their learning capacity gradually declined across the day the nap group they were able to sustain their learning and in fact if anything improve it and the difference between those two groups at 5:00 p.m. was about 20%

so that's certainly non-trivial in terms of if you to say you know here's a new compound that can boost your learning capacity by 20% would you take it I suspect it would probably make some money so that's a demonstration of for learning in memory we did another study very much like that in terms of its design but we looked at your emotional brain and we were showing people different types of emotional expressions and having them rate them and we did that firstly before an appp and then after a na versus um that same time in

sort of midday versus 5:00 p.m. and another group did not nap and sure enough the group that did not nap by about 5:00 p.m. they were starting to rate fearful faces and angry faces as much more fearful and much more angry but if you looked at the group that napped it was different they actually lessened the response to fear and they blunted the normal increase in Anger sensitivity across the day and the nap seemed to boost how positively you rated happy faces so a nap there had the ability to reset the magnetic north of your

emotional compass and there was a beneficial almost added Rose tint to your world viw glasses after You' napped what was also interesting in those two studies two different types of sleep were transacting those benefits in the nap group that was doing the learning the learning benefit that they got wasn't just about them napping and sleeping it was about them having these sleep spindles the more of those sleep spindles that you had the greater the restoration of your learning capacity when you wake up for the emotional recalibration that I described in the nap that had nothing

to do with sleep spindles or even non-rem sleep it required REM sleep to produce that benefit so there are certainly many benefits and we've look downstairs in the body blood pressure cardiovascular measures immune Health they all seem to benefit so at that point everyone may be thinking of course this sounds good not to mention the basics which is your attention your concentration your focus and your energy all improve by way of naps even your decision- making you said decision making yeah even your decision-making is improved so your capacity to make the correct decisional outcomes based

on this weight of evidence that you're facing that's also improved so almost all areas of cognition that we've looked at and many areas of your emotional and mood Health we've looked at seem to benefit by way of a nap at that point you're thinking so then what's the problem the problem is that when you nap you release some of that sleep pressure that's been building up so in the first episode we spoke about a chemical called adenosine and the longer that you're awake the more adenosine that builds up the more adenosine that builds up the

sleepy you will feel and after about 16 hours of being awake you should have lots of healthy sleepiness of adenosine in your brain to put you asleep and keep you asleep and when we sleep we are able to clear that adenosine from the brain so we wake up after 7 to 9 hours and if it's been good quality sleep we're refreshed because we've cleansed the brain in part of that adenosine when you take a nap like a pressure valve on a steam cooker you just Rel relase some of that healthy sleepiness that you've been building

up so the the Dark Side of napping is if you are struggling with sleep and you suffer from insomnia the advice is do not nap during the day because you're setting yourself up for an even higher probability of failure at night why because when you nap you release some of that good sleepiness that we need to build up for you as someone who is struggling with sleep to give you the greatest chance of awai of sleepiness on your shoulders so if you are not struggling with sleep and you can nap regularly I would say naps

are just fine and we can unpack what is an optimal nap and the protocol for what napping should be I would say that's great the only caveat is make sure that you're not napping too late into the day and this is one of the components of the protocol of how to nap because napping late in the day is too close to sleep and you can think of it almost like snacking before your main meal a nap late in the day just takes the appetite edge off your sleepiness so that when it comes time for sleep

you're not as hungry anymore so just keep that in mind but we can unpack perhaps the optimal way to nap if you are going to nap and exactly the dos and the don'ts of that if that sounds of somewhat interest yeah that is uh of immen interest to me and I know many other people I'm a huge believer in naps I've always enjoyed um short naps of about 10 to 30 minutes unless I'm somehow sleep deprived in which case I will sleep for an hour or even a little bit more but I make sure I

set an alarm U really based on advice that you gave me which was to um first of all decide whether or not a nap is beneficial for for for me or for whoever is considering that um but then to make sure that however long that nap is zero to 90 minutes that it not be longer than 90 minutes because the real goal is to not disrupt nighttime sleep that's right which is essentially just a a more long-winded way of saying what you just said so how does one determine the optimal duration of nap um and

in particular to avoid the problem of disrupting nighttime sleep by napping but also this uh rather common phenomenon of waking up and feeling kind of groggy or even I'm kind of grumpy the post-nap face uh or we should call the post-nap expression right right the P NE what's your P are do you wake up um in the and for morning too some people wake up and they're like that that face and then there's the like good morning you know and I think people that wake up with the good morning are particularly delightful unless you're of

the post Snap expression that is kind of the the crumpled face and then you just you don't want to be around those people right no absolutely um yeah and this probably relates to spirit animals and things like that some people wake up like a like a cheerful chipmunk and other people seem to wake up like my Bulldog Costello where it's you know um jowls still in contact with the floor yeah so um P I'm trying to hold it together and not Absol just fall apart it's brilliant please trademarket so firstly to your question how to

optimally nap the word optimal is interesting because when you people say how long should I nap what's the optimal nap duration the question I have back to them is what are you trying to optimize because once I understand what you're trying to optimize I can give you a better prescription non-medical I'm talking about here the a better sort of you know protocol piece of advice for how to nap I mentioned the study about emotional faces in part for a specific reason cuz I told you there the benefit came by way not of non REM sleep

but REM sleep and in our first episode we said that when you go through these on average 90minut Cycles you get most of your non-rem sleep first and then you'll have this bout of REM sleep at the end and it always seems to go that way when you are a healthy normal person you go into non-rem sleep and then you go into REM sleep it's very rare that you ever go directly into REM sleep there are only two reasons when that seems to happen the first is a clinical condition called noopsy where you can have

sleep onset REM sleep and very rare the second is if you are horrifically deprived of REM sleep night after night after night and I let you sleep then at that point REM sleep the pressure for REM sleep has been built to to the point of being almost just insatiable and your brain goes straight into REM sleep but with those two things aside you go into non-rem sleep first so I brought up the emotional study of resetting your sort of mood uh compass because to get that REM sleep you had to nap for a longer period

of time because you had to get through the non-rem sleep first before you get the REM sleep but let's come back to then assuming optimal is for most people when they speak about naps I just want the quick reboot I want my alertness and concentration which are failing because I'm staring at the screen or I just can't concentrate on the work that I'm doing I want my alertness and my concentration to be improved proved I want that sort of slight boost in brain energy where I know I can sustain myself for now a longer period

of time and I've got the motivation which is really in some ways how I like to think about energy as well I've got the motivation the drive to keep going which is just starting to fail me to get those basic things which is what most people nap for aim for 20 minute nap why 20 minutes if I thin slice the nap duration and and those Studies have been done where we look at essentially what's called a dose response curve I give you 5 minutes of a nap 10 minutes of a nap 15 minutes 20 minutes

30 minutes 45 minutes 90 minutes after 5 or 10 minutes you don't really get very much you will wake up and you'll have some degree of improved alertness and your basic reaction time may be a little bit quicker but that Fades very quickly and you don't sustain that benefit once you get past about 15 to 17 minutes now things start to look different you get these nice benefits for concentrational alertness and motivation and those things sustain so once you wake up out of that probably really I would say 20 minute nap at that point you've

got some good wind in your concentration and energy sales for the brain and that will sustain you throughout the rest of the afternoon and into the evening the benefit of the 20-minute nap is that you don't get the PNE trademark Andrew hubman you don't get that almost sleep hangover so some people will say it's strange I nap maybe I'll nap 45 minutes 50 minutes and I wake up and to be honest Matt I almost feel worse after the nap than I did before and I don't understand it it's something called Sleep inertia and an extreme

version of this is in the first two hours of your night of sleep you get a phone call or an alarm goes off and you wake up and you are just kind of lost in the ocean you're looking around at your surroundings you're just in this groggy State you're half awake half asleep and you can respond and you can do things but boy does it feel miserable and it's almost as though you're going from the ground floor right up to the penthouse suite but you get stuck somewhere in between kind of you know floor 13

and it's this rough state if you go out into sleep light stage one nonrem then stage two nonr and just before you get into the very deepest stages of non Ram 3 and four that starts to happen around 30 to 40 minutes for most people but by cutting your nap off at 20 minutes you still get these nice benefits from a good chunk of healthy non-rem sleep but you're not going so far into the cycle so deep into your nonr that when you wake up after 20 minutes you're not in that what we call Sleep

inertia phase that sleep grogginess that sleep hangover phase so it's a nice benefit that you get all of these improvements in your brain but you wake up and very quickly you're back up to operating temperature and you don't suffer that inertia now that's not to say that when you sleep or you nap longer you don't start to get more benefits you do and those benefits are both greater in their magnitude and sustain for a longer period of time they do it's just that you have to understand the tradeoff that you will suffer which is I

will get more bang for my book and I will get more benefits but I will in the first sort of hour or so have to understand that at that point I may even be functioning worse than than that which I did before I even started napping but if you're patient and you go through it the rewards on the other side are significantly better still so that's the first piece of advice and when it comes to how to nap I would say the dose and the timing make the poison and poison is hyperbole in here it's

simply just the poison being how much sleep and nurs you're going to suffer so aim for about 20 minutes that's the do the timing comes back to that which we described before do not nap too late into the day so what's the rule of thumb here for a protocol on average for the average adult I would say don't nap after about 300 p.m. 20 minute naps sometime between 300 p.m. and if you're struggling with sleep don't do this at all if you're not and you're able to get to sleep fine this seems to be a

good ingredient for the basic return on your investment again if you tell me what's the optimal nap duration we need to have a conversation to understand what is it that you're going after here what are the benefits and then I can sort of you know create a finger Buffet Kaleidoscope match to what you need and we can think about the nap duration as a consequence thank you that's very informative um I have a colleague at Stanford who's a Howard Hughes investigator which for those that don't know is a a rather elite club of uh academic

research they have to essentially try out for it they can every 5 years they go up for Renewal it's it's a lot of money which makes gives them a greater capacity to uh take on greater risk uh work higher risk work um and he's also a member of the National Academy and he was one of these people that graduated high school at 15 years of age one of these phenoms and he is so religious about his napping such that when he travels to give seminars at other schools he insists that they schedule a nap time

for him after lunch and in his office um you know at between 12:30 and and 1: p.m. he's napping everyone knows this and um and I mention this because I think that um oftentimes people think of the Nappers as the lazy ones but um his output is um near superhuman and he attributes U much of that output uh to the nap not just the post-nap work that he's able to perform but his ability to uh just kind of manage so many ideas he has enormous laboratory and that's just one example I think there are examples

from sport of um sprinters taking naps on the you know on the side of the the track field I mean so it seems that a capacity to nap is also something worth considering because I think many people listening to this are thinking well I can't nap should I nap you know um and can one teach themselves to nap so that's the question um if one would want to explore napping and um is that something that one should even consider doing if you don't have a propensity to nap should you avoid it if you want to

try naps how could one teach oneself to nap you just mentioned earlier uh lying down uh relates to body temperature body temperature uh relates to sleepiness and then as a third question I promise I'll repeat these if we need to uh as a third question I'd like to have a little bit of a discussion about some of the pseudo naap states that um I certainly am intrigued by you know for instance just lying down and I'm doing a progressive bodily relaxation things like Yoga Nidra uh non-sleep deep rest which is an acronym ioin simply to

to um make it clear what I was talking about but it's very similar to Yoga Nidra um things of that sort in other words but simply should everyone think about having an early to mid-afternoon protocol to reset their cognition and their body we call it a nap but does it have to be a nap and if we're not good Nappers should we try and if so how should we go about it yeah so TI your three questions firstly if you're not a natural Napper should you start doing it um if you want to start doing

it how should you do it and then the third is is there some kind of you know substitute for a like kind which would be these Li these I I'd love the phraseology that you use these Lial states do they mimic that are they different to that how should we think about those the first thing I would say to point number one if you are not a natural Napper don't necessarily Force yourself to be as long as you're getting the sleep that you feel you need at night and you feel refreshed and restored during the

day and you don't have that sort of postrenal drop to the point of thinking I almost need to nap during the day there is no pressure based on anything I've been telling you for you to start napping nor should there be any reason that you do start napping but let's say that you want to try what would be the right protocol to improve and increase the likelihood the best way you can do this is to mimic nighttime as best you can so wherever you are if you can shut off the lights make sure that you

can block out you know curtains blinds if you can't do that fully and many people won't be able to develop an IM mask procedure um so put an IM mask on make sure you block out noise earplugs you can use a sound machine if you want and we can speak about sort of sound machines and whether or not they're good or bad on sleep and then you can lie down make sure that you try to take your shoes off and get under some kind of a blanket because we're so Contex cued by having something wrapped

around us called a blanket or a duvet that to do it without that if you are not a natural Napper can help you again that some people will say I can just kick my feet up on my desk sit back in my reclining chair in the office and I can fall asleep that's great but if you're not a natural person I'm just trying to tell you things that increase the probability of that and then set the alarm I like your idea of making sure that if you do fall asleep you don't accidentally go too long

and then just feel miserable so mimic the conditions that you're trying to get that you would normally get at night that will increase the probability mask out noise mask out light kick your shoes off have some kind of a blanket wrapping around you that's probably the best and then time it based on this sort of post pral drop you will know yourself everyone has fallen prey to it you know W it's usually around about 3 4 p.m. that I do start to feel this decline or it's around 1 p.m. try to match it in accordance

with that so those are the first I think two questions should you not necessarily if you would like to and I'm not normally doing it how can you do it the final point I think is fascinating which is these alternate states of conscious brain activity the most obvious is when we're awake and when we're asleep those are the two most dramatic changes in Consciousness that we experience on a daily basis short of anesthesia I've become like you very fascinated by these sort of both meditative States or these linal states I think at some point you

and I should collaborate and we should do some work and really unpack this but the reason I find this interesting is because I'm going to guess you are having sleep likee States but you are not fully asleep how would I Define a sleep-like state what we've learned is that your brain the way it sleeps isn't on mass it's not as though your entire brain sleeps different territories of your brain can sleep in different ways and what we've also known and there's some argument even individual brain cells seem to have a period where they go into

sleep and these individual neurons will start to show what look like these beautiful big powerful deep slow waves in terms of their firing rate at least in terms of those neurons firing away I bring this up because if that means that your brain can have local sleep rather than Global sleep if you are in global sleep you're out like a light you are a sleep but perhaps these Lial States the reason that they give these benefits is because you are still awake not Global sleep so if you're in global sleep you're asleep but you're awake

so you're not in global sleep but you may be having local sleep now using special um setups in my laboratory we can apply tens maybe hundreds of electrodes all over your head and we can map the the sort of the the different places where your brain is having sleep in much higher resolution so rather than a you know 480 DPI movie on YouTube I'm now in 4K resolution I can really dismantle what's going on um analytically in your brain I'm going to guess that when you're going into these states and you report coming out of

those states and I ask you on a scale of 1 to 10 how would you rate that as an experience based on your common experience the greater the intensity of the lional benefit and state that you experienced I'm going to predict is directly related to the extent of this this local deep non-rem slow wave sleep that's happening you're still awake but some parts of your brain for maybe seconds of time or maybe even tens of seconds of time I'm going to bed will be oscillating in what look like slow wave sleep deep sleep States and

if all I would be able to look at is that one part of your brain and that small cluster of electrodes and someone said to me is this person awake or asleep I would say oh they're asleep they're in deep sleep but then if you slowly reveal and back out and show me the rest of the brain and what it's doing I would say oh my goodness no this person must be awake but that local territory that District up there in their brain they were having slow wave sleep I think that's what we could find

and that may predict some of the benefits that you get some of the productivity energy benefits by the way I should note that with all of this nap racket NASA figured this out back in the 1980s they were looking at ways to optimize their astronauts because when you are up in orbit depending on what orbit you're in you are rotating around the planet maybe 10 and 20 times per 24 hours so you're seeing 10 to you know 20 sunsets and sunrises so your sleep is a total mess and you can safety check almost everything in

terms of Technology but the one weak Link in a space mission is this thing called the human being that's where errors typically happen so how do you drisk a human error up in space because if you make an error up there I mean on the ground not great up there kind of catastrophic you can try to optimize their ability to sleep and their ability to maintain Focus concentration alertness and productivity and what they found was that these naps produced almost a 20% boost in short naaps 20% boost in their alertness and almost a 50% boost

in their task productivity and it was so powerful that it translated to the terrestrial um employees of NASA on the ground and it became what was known as the NASA nap culture and from there on we had what we called power naaps Power naaps by the way why are they called power naaps and you think well just because it Powers me up it's a good idea but it's wrong it has a very specific story a fascinating one two legends in my field David dingis uh and Mark Rose kind they were looking at how to instigate

risk mitigation not in astronauts but in pilots who are doing long haul flights because the most dangerous aspect of a long haul flight is when it is coming down to land and that's when they can sometimes have these things called a catastrophic hole loss which is a euphemistic phrase for a terrible plane crash and they were trying to say how could you use nap strategically to drisk that and improve their alertness and they asked a very interesting question if they can nap for only a certain period of time because they have to be at work

on the plane at the for the rest of it when should you place that nap should you do it at the start of the long call flight in the middle or towards the end and most people would bet like they I think did it's best to place it at the end when you're really starting to struggle get that boost and then you wake up you're not in sleep in OA cuz it's been brief and then you're energized for landing they didn't find that they found that the most optimal time to nap was early on in

that long haul flight and it sustained them throughout the rest of the flight now they took their findings to the FAA who were funding the work um and the Federal Aviation Authority here in the United States and they said we've got some great findings and we think we should implement this and we would like to use a term to help Pilots understand this and it's called prophylactic napping and of course there were many Chuckles throughout the room perhaps inappropriate and they just said look you've got to understand our Pilots the you know kind of alpha

male guys and if you're starting to say you need to prophylactically NAB it's not going to be adopted that's a nogo so they looked around the room because it's an alpha male culture it's a mostly masculine culture at that time they said what could we and there's a lot of beard stroking and they said I've got it power naaps it's got to be about power and so that is where if you've ever wondered where the term power naaps come from it's not because it reboosts your power which it does and boost it back up it's

because there was Chuckles at the time prophylactic napping I'd like to take a brief break and acknowledge our sponsor eight sleep eight sleep makes Smart mattress covers with cooling Heating and sleep tracking capacity many times on this podcast we discuss how in order to fall and stay deeply asleep your body temperature actually needs to drop by about 1 to 3° and in order to wake up feeling maximally refreshed and energized your body temperature needs to heat up by about 1 to 3° eight sleep makes it very easy to control the temperature of your sleeping environment

so that it's easy to fall and stay asleep and wake up feeling refreshed I started sleeping on an eight- Sleep mattress cover several years ago and it has completely and positively transformed my sleep so much so that when I travel to hotels or airbnbs I really miss my eight sleep I've even shipped my eight sleep out to hotels that I've been staying in because it improves my sleep that much if you'd like to try eightsleep you can go to 8sleep.com huberman to save $150 off their pod 3 cover eight sleep currently ships to the USA

Canada UK select countries in the EU and Australia again that's 8sleep.com SL huberman the naming of things fascinates me especially in um the uh landscape of health and well-being um also um and that's one reason why um having become a real fan and practitioner of Yoga Nidra which I think translates to yoga sleep which is this process of lying down for a period of 30 to 60 Minutes Progressive relaxation this is these are scripts that are readily available as this is a a uh age-old practice um in in India um that is meant to restore

mental and physical Vig Vigor by placing one into one of these Lial States the um and I have great respect for the uh ner tradition um but um sometimes the names are a separator so people who hear Yoga Nidra and they think oh it must be yoga movement and that's of course not true or they think um that there must be some mystical component to it which is not necessarily true sometimes they include intentions and things like that but often not so that's why I coin this um uh phrase non-sleep deep rest which is essentially

maintains the critical components of Yoga Nidra um but doesn't include intentions and um has these shorter uh 10 or 20 minute um protocols so it'd be um great fun and um I think very interesting for us to do that project to explore what are the brains uh activation States or deactivation States as the case may be in these um non-traditional or Lial State uh practices now um along the lines of power napping specifically and the naming of power napping I think it's more than than just a a um anecdote because I think it is very

important for people to understand that um that these protocols these tools that NASA and that Laboratories have have developed um often times are are for other purposes but they translate to a kind of broader significance and what I'm hearing and what I'm starting to integrate as we have today's conversation is that it seems that there is pretty good reason to ex at least explore basic sleep right that that for the non-nappers to to really think about whether or not they would like to explore napping as you mentioned they don't have to and then for people

who are already um napping to really think about the placement of that nap uh within the day and the duration of that nap what you told us a few moments ago suggests that I should be doing or anyone that's doing naps or entering these Lial States like nsdr might want to shift them a little bit earlier than uh the period in which they first become sleepy to take that nap is that right I mean like so for instance should I do as my colleague and you know finish lunch and and lie down for 10 15

minutes um rather than wait until 2 or 3 p.m. is that is that something that that could make a meaningful difference I think it could and I think it really again depends on how much of a struggle sleep becomes in the evening for you if it is becoming the later that you nap if your sleep becomes either a more difficult to initiate in the evening or maybe you don't have any problems falling asleep but for some reason when I look back I'm now starting to wake up more throughout the night that in part again it's

not just that if you nap late in the day you struggle to fall asleep you may not the other consequence that can happen which is non-mutually exclusive is that you then stay in not as deep as sleep and your sleep is more some more fragile in that sense so the probability that you will wake up because because you had the nap so late in the day is higher in the middle of the night and then when you wake up like many of us do and you go to the restroom or It's Perfectly Natural but the

speed with which you can then fall back asleep is compromised why because you've jettisoned some of that sleepiness by way of the nap and there isn't as much to take you back down into sleep after you've woken up so I would just say that if you are seeing that pattern that the later napping that you're doing if you're doing that and again there's no reason that you need to nap only if you choose to nap if that's the case then consider not necessarily obviating the nap that may not be required just bring it back earlier

take it after lunch see how things work out do the experiment and when you do the experiment make sure that you do what I would describe as the onof on experiment which is where you're napping as you normally do and you've noticed perhaps some problems with your sleep then do so that's sort of the the well it's sort of the on off on phase so then change your nap protocol and move it earlier so now you've Switched Off Your Standard protocol and you've moved on to something different so you're on your standard protocol and then

you come off it and when you come off it meaning you go to an earlier nap and you say gosh things do seem to be better maybe he he had something there and it does seem to improve good but I don't trust that because maybe it's just a placebo effect that you you know hear some dulit British tones and you get convinced that maybe that would work and you've now instead after about two weeks of doing that and things have improved go back to your original schedule go back on to your original protocol I'm not

as interested about the fact that things got better when we changed it I'm interested in the question do things get worse when we stop it and so when we stop the intervention if things got worse again now I'm I'm believing it a lot more so just as a tip if you are a self- tinkerer and you don't have to do that but if you're idiotic like me and a scientist and you want to do it with this city riger that's the way I would suggest doing it I don't think it's idiotic at all I think

it's systematic and what you just described is uh both a negative control and a positive control experiment so you're you are a scientist through and through are there any individuals that should absolutely avoid napping you know I'm heard lore of you know um elderly folks um folks with certain conditions um you know can't imagine um which but um I'm sure you'll tell us that for whom napping is harmful to their health it's a very I think interesting question because the strongest evidence comes back to that which we we've mentioned before which is insomnia and really

the recommendation there is just avoid naps it's and what's problematic about insomnia when you are having such tough times with sleep at night and you are just dragging through the day it is miserable and I am you know I I'm very protective of my sleep um for the most part I sleep pretty well but I've I'm I'm not immune to the vagaries of sleep I've had two bouts of insomnia throughout my life both have been what we call reactive insomnia reactive to an event or something happening and I know how just desperate and hungry you

are for sleep and if it's happening week after week month after month I'll just do anything to get sleep when I can and the Temptation therefore to nap when you are suffering from insomnia is that much higher and therefore the advice is that much harder to adopt but trust me that is one of the components that we have in the psychological treatment bucket that we use for insomnia which is called cognitive behavioral therapy for insomnia or cbti for short and you can just look it up or um on my own podcast I done a six-part

series on on uh insomnia so I would say try to back away in that circumstance but you brought up a another example which is in aging there I think the evidence is a little less causal so you have to be more cautious about recommending the absence as I was with insomnia of abstaining from naps but the data has now become quite strong that when you get past about 65 years old and you look at napping behavior in large epidemiological studies and you say is there a positive benefit in aging for napping or is there no

benefit at all and they looked at that because they thought well that perhaps based on the work in healthy adults that I've described that would be good for older adults not only did they find that it wasn't good they found that it was deleterious that napping in older adults was predictive of worse Health outcomes and it also seemed to predict a higher likelihood of early mortality so at this point we're thinking well how does that fit with everything you've been telling us it comes back to this notion of bad sleep at night it's probably not

necessarily that napping during the day is bad for older adults it's that the Naps reflect a problem with the night of sleep for older adults and as we get older something I didn't mention during development was that yes we get this sort of State Lael ratio of 4 to1 of one part REM sleep four parts non-rem in our 7 to9 hours and I described these changes in rem early in development I didn't mention two things about non-rem slow wave activity first as we go into our teenage years and we shift our sort of timing of

sleep where we want to go to bed later and wake up later that's biologically determined it's not teenagers fault something happens with their deep sleep however their deep sleep starts to do a different or different action to the brain that REM sleep was doing as an infant I said that during infancy we have huge amounts of REM sleep and were growing sinapsis syap Genesis and we wiring up all of those new territories all of these new neighborhoods with fiberoptic cable but let's say that you've now run the experiment across many years through until teenagehood of

those neighborhoods and you've been measuring the bandwidth consumption of each individual house and you've started to realize well I wanted to create a big spread across the brain and then I'm just going to let experience over the next years time tell me which parts of the brain seem to enjoy that high bandwidth and which parts don't seem to use it very much and as we go through into our teenage years we go through something called synaptic pruning where the brain actually calls and takes away copses from certain parts of the brain it seems to be

that this change in slow wave sleep that happens around these adolescent years is performing the act of final cortical maturation that it's downscaling the synapses and fine-tuning the brain so you've got this beautiful efficiency and now you've throttled back some of the bandwidth from some of those neighborhoods because they just don't use it very much and you can move it over into the territories that are demanding more bandwidth and net net the brain is downscaled but it's improved its efficiency in the sense that those regions that need it and are working hard based on what

we think this organism has been doing over the past you know 13 years that's where we need to now place our bets but as we get through into our older years and this will come back to this issue of napping don't worry stick with me here folks um the reason is that as we're getting older our sleep de deines but it's not just all sleep declines deep sleep declines most dramatically and we all think of aging from brain perspective as cognitive decline that our learning and memory abilities begin to fade and Decline and they do

but I would argue that a physiological signature of Aging is that your sleep gets worse and particularly your deep sleep what's perhaps concerning for people listening to this right now is that that decline in deep Sleep doesn't start happening in your 60s or your 50s or even your 40s we can start to pick up that great sleep decline beginning in your mid to late 30s and then it just decreases and by age 50 you are down to about 50% of the deep non-rem sleep that you were having when you were 17 or 18 by age

65 and over or certainly by age 75 you are down to about just 5% of the deep sleep that you had when you were 17 or 18 which is a stunning decline what that means comes back to the first episode we spoke about the four macros of good sleep quantity quality timing and regularity one of the measures of quality that I described to you was this electrical quality of deep sleep the other measure of quality sleep I spoke about was how consolid ated and consistent your sleep is versus how fragmented your sleep is the measure

of Sleep Quality is markedly compromised as we get older we're waking up many more times our sleep is much more fragmented and therefore our sleep efficiency is worse and we've got this huge decline in our deep non-rm sleep so no wonder then when you are awake during the day as an older adult Your Sleep Quality is so compr promised at that stage you perhaps try to compensate by way of napping but that compromised quality of sleep that you're having at night is probably the reason that you start to get sick more that you have a

higher probability of illness and disease and why also you probably have a higher risk of premature mortality so in other words it's the bad quality of sleep at night that leads to this behavior that we call daytime napping in older adults that seems to indirectly suggest oh my goodness it's daytime napping that's bad and that causes these problems when in fact it's that daytime napping is a proxy for the bad sleep that's happening at night and it's really the bad sleep that's happening at night that is more directly related to the health and mortality concerns

in older adults so that's why I think right now as a field I'm still open to evidence that napping for some reason that we just do not understand right now is problematic and does causally predict worse health and a shorter lifespan in older adults I think the best evidence that we have right now is that it's actually the bad quality of sleep at night and thus we should not be necessarily jumping to recommendations that all older adults should stop napping I think we need more evidence and I'm open to both sides of that let's talk

about caffeine uh I've heard the ter term is it napino yeah I I I think it um refers to a practice of drinking some caffeine then laying down for a nap and then supposedly waking up um feeling more refreshed my understanding and you'll tell us more of course is that caffeine um is effectively uh an adenosine antagonist although it's a competitive Agonist and you'll explain I'm sure um and napping as you mentioned before uh removes some of the Sleep pressure AKA uh wipes away some of that uh adenosine that's accumulated um both of which sound

great but as you mentioned earlier there's a warning there as well uh the warning label on uh both those things should be that having sufficient adenosine built up in your brain is one of the ways in which you feel sleepy at night and fall asleep and stay asleep yeah so what's the story with caffeine how does it work uh to make us feel more alert and um what is the rationale for the nappuccino the nappuccino also known as the caffeine nap caffeine is a very interesting compound in relationship to sleep and wake obviously everyone knows

that caffeine can help you stay awake it's no coincidence that those two words that you've used about these chemical compounds caffeine and adenosine sound the same it's because the re receptor that or the receptor systems that caffeine Targets in your brain are the adenosine receptors and you think well Matt was telling me that the more adenosine that builds up in other words the more adenosine that's latching onto those adenosine receptors in your brain the sleepier that you feel and I'm telling you that caffeine works on those same receptors that doesn't make sense caffeine if it's

working on those same receptors should increase your sleepiness it doesn't because it when it binds onto those adenosine receptors those welcome sites in the brain it simply blocks them it doesn't deactivate them nor does it activate them it simply blocks them so think about it almost a little bit like um a room that's full of chairs and at some point these adenosine which is one collection of people with the name badges of adenosine they would normally like to come in and start sitting down on those seats which are the adenosine receptors and as they sit

down on those seats you're building up this signal of sleepiness well caffeine which is another group of people with caffeine badges they race into the room and they start to hijack the seats and they start to sit down on them and all of a sudden adenosine can't find any seats to sit on so your brain is still flooding that room with adenosine so the adenosine is still building up but the reason that you don't feel sleepy anymore when you've had a shot of caffeine is because caffeine is raced in it's latched onto the receptors and

it has essentially hit the mute button on your sleepiness so now your brain was thinking gosh I've been awake for about 13 or 14 hours I'm starting to feel it I'm just going to take a quick espresso shot and you get that you don't think well hang on a second you know 20 30 minutes later I don't feel as tied anymore why it's not because caffeine came in and removed the adenosine it didn't caffeine has come in blocked the sights but the the adenosine is still building up and then at some point the caffeine wors

off and therefore not only do you go back to the same level of Denine of adenosine that you did 2 hours ago it's that plus the additional 2 hours of adenosine that has been building up and what you experience is something called a caffeine crash and now you need even more caffeine not just to get you back to where you were but to recover the crash that you've had and go further caffeine in relationship to the caffeine nap though the napino is relevant because of its timing caffeine has an instigating action of around uh 12

14 to 17 minutes so when you come through in the morning and you grab your first cup of coffee and within the first four or five minutes you you say I just I just feel better I've just had a couple of sips I've had half a cup of coffee and I already feel better I just needed that if it's within the first five minutes that you're experiencing that it's got nothing to do with the caffeine because the peak plasma concentration of your caffeine is not going to arrive with you until about you know 12 to

17 minutes so why do you feel better some of it is Placebo because you're smelling the coffee and you associate it with the L it's really not that though or or um when you say Placebo I also wonder whether or not it's possibly a a conditioned effect you know like a pavlovian thing because the smell of the coffee the taste of the coffee the the hum of the machine the walking into the cafe to to um and ordering it from the Barista also creates an anticipatory arousal like here the the alertness is coming and in

that anticipation there's its own form of alertness I think that's that's certainly a big component of it the other component however if you look at the data is that it's got nothing to do with the caffeine in that moment it's the temperature that most people take their caffeine warm either it's tea or it's coffee or it's perhaps something else that Andrew hubman would drink but many people yamate since since I was 5 years old I don't I don't know if I should have been drinking uh caffein yerbamate so young maybe even four years old there's

a photo of me on my grandfather's lap drinking out of the mate gourd half my family is Argentine and um so I was caffeinated from a young age this brain developed in a caffeinated millu this explains so much about what I've known of you over these no I'm kidding you um so um but we need to speak later no so what's interesting about that is it's the temperature and I told you in the first episode that we need to cool down to stay asleep but we need to initially warm up to fall asleep because warming

up at that moment I was telling you is warming up at the periphery a warm up to cool down to fall asleep so you need to warm up to cool down to fall asleep then you need to stay cool to stay asleep and then you need to warm up to wake up the warming up to cool down to fall asleep is not warming up in the middle deep core of your body it's about warming up the hands and the feet and the head to dissipate the heat hence warm up the outer surfaces to cool down

the inner core to fall asleep but then I told you you have to warm up to wake up and when we take a hot drink in the morning usually caffeinated the change in your core body temperature can happen with within a handful of minutes so the initial benefit that you get from the hot cup of coffee in the morning or hot tea is from the temperature rise and then you get this beautiful second kick from the caffeine itself and that caffeine can then sustain for a longer period of time so we mentioned this problem with

napping that even at 25 or 30 minutes of a nap you wake up with that kind of grogginess that sleep inertia and what however if I could give you the benefits of a nap and have you come out of the nap with zero sleep inertia and that's what some folks started to cleverly think about what if I could look at the timing of the optimal nap maybe 20 minutes and think about the timing of when Peak plasma concentration of caffeine emerges and I told you really starts to kick into gear around 17 minutes and it's

in full swing by 20 what if I was creative I'm going to withhold from saying idiotic enough but creative enough to get into bed just before I turn the light out for my nap in the afternoon I Swig a quick espresso light goes off I close my eyes eye mask earplugs and I'm going to drift off fine because the the caffeine is not going to kick in and for another 17 20 minutes perhaps at its full threshold so now you you fall in to sleep and you're going down into sleep and if you perhaps don't

make it too large in terms of its serving the temperature change is not going to affect you in a negative way and then just as your alarm clock is about to go off after 20 minutes you're on the beautiful ascending swing of upward plasma concentration of caffeine and you get ejected out the other side with both the benefits of the nap together with the benefits of the caffeine so you get your cake and you can eat it too you get the nap absent the Sleep inertia and hence this created what we call the caffeine nap

I love it the nappuccino the the nappuccino um maybe I'll give it a try uh this is the first time I've ever heard the um the rationale and the the the fine structure of the nappuccino but it makes sense um uh at a logical and mechanistic level I have to ask is there anything besides caffeine and sleep that can clear adenosine you know can exercise clear adenosine can uh cold shower clear adenosine I mean and I understand that there are a bunch of competing mechanisms in the body like presumably a spike in norepinephrine or adrenaline

or both is going to impact the adenosine system I I once heard a great quote um from a former uh member of the National Academy of Sciences a brilliant guy he said you know a a drug is a substance that when injected into an animal or a human produces a scientific publication meaning meaning it is it is rare to find a paper that doesn't see some effect of some drug especially on sleep I'm told as I recall if you put aspirin REM sleep into PubMed you're going to see some effect on REM sleep people take

aspir pretty much any substance that one takes is going to to alter um some feature of sleep or of wakeful States if one is looking with a fine enough uh instrument or is that an overstatement no I don't think it is an overstatement and it comes back to the first episode where we described the complexity this incredible beautiful physiological ballet certainly one of the recommendations when people say I get this afternoon this post prandy will drop in my alertness what can I do I say you could nap but another way is just get outside and

walk around be physically active some of that has to do with the fact that you'll probably get some daylight and daylight can be a stimulator of alertness as long you've told us and educated us on we also know that physical activity by itself can increase the amount of endorphins and dorphin and those are wake promoting but none of those are really necessarily going to be altering adenosine they're simply overriding the adenosine that is still building up it really does seem to be for the most part at least as all that I know it's only sleep

and particularly non-rem sleep that has the capacity to or give the brain the chance to remove that adenosine now what could be interesting I think is two circumstances one is where your brain becomes less metabolically active for another reason and I told you that it's not joring it's not as though during deep non-rm sleep that there is some special pulsing cleansing mechanism for adenosine there is a cleansing system called the glymphatic system which removes the toxic metabolic byproducts of the waking day wakefulness in some ways is biochemically low-level brain damage and sleep is sanitary salvation

in that regard knew um but which is again it's humoristic and it's it's it's going too far but it makes a point the idea here however is that it's not that there is a special system that is removing the adenosine during deep nonm sleep it's just that your brain is less metabolically active and therefore it's not producing as much adenosine so the natural mechanisms that are always occurring in the background to be clearing adenosine and degrading it simply get the chance to do that just as effectively as they have but you're no longer working against

the opposite tide that is growing the adenosine now the adenosine increase has dissipated because you're no long longer metabolically active during deep sleep and you get the chance to cleanse it all of which is to say therefore that and I think that would mimic that such as for example anesthesia my guess is that you probably do jettison some sleep pressure when you are in anesthesia I also think that these Lial States non sleep deep rest could be a fascinating territory there because at that point I'm going to guess and we'll be able to see with

the e G and we may also be able to do some Imaging depending on how we you and I design the study to look at what changes in the brain in terms of its activation State my guess is that if it does put you into something like slow wave activity patterns that means that those territories of the brain are metabolically less active and that allows the brain to dissipate the adenosine so to your point I don't think things like necessarily exercise or light change adenosine level they do give a nice alertness benefit for other reasons

but is there an alternative way of dissipating adenosine yes I think anything that mimics a non or a less metabolically active brain could produce these beautiful adenosine benefits thank you for that this brings me to a question about the period immediately after waking from the nightly bout of sleep um I've been uh touting the benefits of delaying one's caffeine intake by 90 to 120 minutes after waking there's a little bit of a misconception out there I think people um ran with the ball uh assuming that I was mandating this or think or suggesting that everyone

should do this and that's simply not the case uh I actually wake up and I'll hydrate and drink caffeine very close to waking if I'm going to exercise soon after yeah um which I often do um but I've experienced and I know others um have experienced if they are not going to exercise immediately or they don't need caffeine to exercise for whatever reason I've heard these people exist I'm no such M mutant um that delaying their caffeine intake by 90 to 120 Minutes in some cases can offset the afternoon crash now I want to be

clear some of that may be offsetting the afternoon consumption of more caffeine because by delaying your caffeine intake in the morning then perhaps there's less of an incentive or requirement to drink caffeine in the afternoon and all of which dominoes to as we'll talk about more in the series to better sleep at night because you you're not ingesting caffeine close to bedtime but at risk of taking a massive tangent here's what I'd like to know based on what you just told us if indeed sleep and lower metabolic activity in certain brain regions can help reduce

adenosine levels in the brain one could imagine that upon waking it is either a step function from okay you know let's say at um 5:45 a.m. somebody is asleep and adenosine is still being cleared away because they're asleep and then they wake up boom does adenosine clearance immediately stop well for people who have that um crumpled face uh grogginess um and they wake up at 5:45 maybe even by way of alarm although we don't uh suggest that right and they stagger into the kitchen and um ordinarily they'd make their cup of coffee but they're in

a pseudo sleep state yeah so it stands to reason that they're still clearing adenosine now if they are to drink caffeine right away then they're as you pointed out going to block those adenosine receptors and there's going to be a continued buildup of adenosine as opposed to a clearance of adenosine so this was um part not the entire reason but part of the rationale for suggesting that people at least explore delaying caffeine slightly and then there are things like the cortisol rise and Etc but um does that kind of framework at least make logical sense

that doesn't mean it would hold up in a randomized controlled trial but given that we're talking about essentially zero risk protocols here um what are your thoughts on that I think it is good advice for people to test and it's good advice for two reasons the first is that which you describe in some ways by taking caffeine on early and masking that adenosine also caffeine can make your brain more metabolically active which means that you're going to build up more adenosine during the day which means that sleepiness is going to arrive earlier which means that

perhaps that postprandial drop is going to be you know harsher and you're going to perhaps then need to self-medicate with more caffeine to and so goes the Vicious Cycle so I think that's one thing to keep in mind I think that's one hypothesis I think the second hypothesis for me or the second reason I would advocate for that is if you've been using caffeine that way for a long period of time you may also be masking the quality of your sleep because you wake up you immediately medicate with caffeine and you are alert you're awake

and you think well I looking back on my night I'm awake now after my caffeine and now is the important part of that sentence I'm awake now so there's nothing wrong with my sleep is that true maybe it is maybe it's not maybe if you abstain from caffeine through and you have to get through the detox period it's not going to this is not the right test immediately but do it for about two weeks and then at that point once you're free from the detox and the withdrawal now you're in a somewhat naive state where

you're taking your caffeine on I'm telling you to stop caffeine you're taking it on at 11:00 after you've woken up let's say 7:00 in the morning at that point we've now got this nice Clear Window that has been consistently happening between 7 to 11: in the morning and I'm going to ask you now do you feel rested restored and refreshed and can you operate with cognitive acumen and skill in those first morning hours now don't forget we've got to get past the natural sleep and Heria period in the first 90 minutes but after the first

90 minutes of waking up absent of caffeine let's say by 900 a.m. in the morning are you functioning well because if you're not and you still think you know what I don't feel restored by my sleep I feel unrefreshed I want to then start asking you let's take a look at your sleep and let's see how we can get you to a more refreshed state and by using caffeine first thing in the morning you don't give yourself the chance to test whether or not subjectively you sense your sleep is good quality now you don't need

to do this forever you can just do a test for a month and be asking that question and if all is clear after you've got through withdrawal and you've got past the first 90 minutes after waking up and you tell me now in this more caffeine naive state in the first few hours I feel rest I feel refreshed I feel restored by my sleep then that's great we don't need to be concerned about your sleep so that's the second reason I like it because it gives you the opportunity to test out whether or not your

sleep is of good quality or not I should also note by the way that I mentioned I've changed my mind on caffeine and its use and this comes back to I just raise it because you had said I made this suggestion and it wasn't binary it wasn't dictatorial you don't have to to do it I wasn't saying that everyone needs to do it and in fact even I will you know tweak my schedule if I'm doing one thing in the morning I will take on board caffeine fairly soon if I'm not I will hold off

I came out the gate when I first published um a book and it and I was very dictatorial about it I and I was very mono I was very binary you know it was sleep is absolute and it's it has to be this way and no other way I was not in favor of caffeine and I was telling people about the dangers and there are dangers to your sleep and we we can speak about those but it was a little bit too heavy-handed I've changed my mind for at least two reasons first that's not the

way Society works or people live so there's no amount just like technology in saying leave your phone outside of the room for 2 hours before bed and don't check it for the first 4 hours that that Genie is out the bottle so the reason I have changed my mind on caffeine is because if you look at the data on on caffeine it's stunning for Health it on almost every metric that we can measure drinking some degree of caffeine is beneficial now there is a I knew it there is a U-shaped function to this which is

once you get past sort of three or four cups of coffee then you start to go in the downward Direction and things aren't so great the contradiction however was that I was telling people caffeine not good for your sleep and sleep by the way is wonderful for Health it transacts all of these benefits that we have and will discuss in this series but then you compare that relative to caffeine and caffeine transacts many of the same health benefits so how can you explain that Mr sleep scientist well if you look the the data is very

clear it's not the caffeine that's the benefit most people take on board caffeine by way of a cup of coffee and the Coffee Bean is Pack full not just of caffeine it contains a whopping dose of antioxidants and because of our deficient Western diets were so absent of these antioxidants that the humble cup of coffee has been asked to carry the Herculean weight of our antioxidant needs on its shoulders so no wonder it by itself carries such a strong Health signal because it's providing you with this wonderful dose of antioxidants in addition to caffeine case

in point if you look at decaffeinated coffee you still get the antioxidants but now now you don't get the caffeine and lo and behold you get many of the same health benefits it's not the caffeine it's the coffee itself so I think that is a a perfectly good reason to justify caffeine but again just like naps the dose and the timing make the poison if you're not someone who's sensitive to caffeine then having a couple of cups of caffeine and trying to step away from the use of caffeine I would argue somewhere between 10 to

12 hours before you expect to go to bed depending on your sensitivity and it is different across people and we know that it's genetic there is a specific um what we call polymorphism which just means A variation in a particular Gene and if you look at variations in that it will predict whether you are someone who is very sensitive to caffeine or not very sensitive to caffeine and it comes down to how quickly you can essentially metabolically remove that caffeine from the system so if you know that you're a very sensitive person I would probably

argue try to stay clear maybe 12 to 14 hours if you're someone who is not as sensitive then you could maybe go to 8 hours the danger is for people who say look I'm one of those people who is you know really just not sensitive to caffeine at all and I can have an espresso with dinner and I fall asleep fine I stay asleep fine so it's really not a problem for me I would say that that that may be true but the inherent danger here is that and we've done these studies if I give

you a dose of let's say 200 300 400 milligrams of of caffeine in the hours before bed which would be a large you know strong cup of coffee or you know two espresso with dinner some people can fall asleep and some people stay asleep but the amount of deep sleep that they have is compromised in fact it can drop your deep sleep by up to 20% now the danger is that you wake up in the morning and there was no signals in your sleep that said you had problematic sleep because you're not aware of how

much deep sleep that you had that's the reason that I think you know sleep trackers can be helpful in some ways but you then wake up and you don't feel as refreshed and restored but you don't remember having a hard time falling asleep or staying asleep but now you find yourself reaching for three cups of coffee to wake up in the morning rather than the standard two and so goes the Vicious Cycle so and also you see an interesting interrelationship we did a recent study we just published in Wall Street Traders it's not just caffeine

use it's also about alcohol use in the evening that people who overmedicate with caffeine during the day they then need something to bring them down at night and the principal depressant agent and depressant not in the sense of psychiatric depression but in the sense of brain neural activity depression is is alcohol so you get this classic cycle of uppers and downers I need my uppers during the morning my caffeine and I need my downers at night to lull me into sleep and it's this really interesting trade-off which we we saw in these Wall Street Traders

so coming back to the notion of caffeine though I am favorable of it in terms of its health benefits I think it's very very clear just be mindful of the dose and be mindful of the timing dose try to not exceed about three cups of coffee timing understand your sensitivity there are certain genetic tests if you really want to get nerdy that will tell you if you have this sensitivity or not but you will probably know it and therefore just say okay I'm not that sensitive I could probably go 8 hours or as close as

8 hours before sleep or 10 hours if you're very sensitive 14 15 hours and keep it to one cup um so those are the ways that I would see moderating caffeine and changing my my mind on caffeine which just comes back to your point where you were saying I made this recommendation about caffeine I want to make sure I modify that so people don't get confused I certainly um needed to make a modification to my stance on caffeine so thank you for letting me say that which is a long uh winded way of of getting

around it but does that help a little bit that does help it um very much thank you for that um addendum to the legislature [Laughter] okay so you told us about the power nap and you've told us about the caffeine nap the so-called napino yeah what are some other types of naps that can be beneficial for Sleep awake cycles and alertness so you can think about the caffeine nap as trying to amplify it sort of a nap plus as it were but to your question the study that comes to mind there was a brilliant investigation

Herculean in its study design from a great sleep research group out in Japan and they asked okay the nap is good the caffeine nap may be a little bit better but can we go further um and so they designed a series of studies they had five different experimental groups and they tried to basically create a stack a stacking system they had across the 5 groups there was a non naap group that's the control then there was a nap group then there was a nap plus caffeine group then there was a nap Plus Cold face and

cold handwashing immediately after you wake up I'll come back to explain why that we think that works and then the final group was a group that was a nap plus bright light and again thank you uh me offering this as the general public to you Andrew hubman for for your light Revolution so it was bright light at 2,000 looks immediately afterwards so they had five groups again there was no nap group nap group nap plus caffeine nap plus cold hands and face washing nap plus immediate brightlight the cold hands and face washing is interesting I

told you before that there was this three-part story to to the sleep wake equation that you need to warm up to cool down to fall asleep stay cool to stay asleep warm up to wake up and I'm saying warm up to wake up but use cold water on your face and your hands don't forget that warming up when I say it in the morning is warming up at the central core of your body you reverse engineer what you did in the evening I said warm up to cool down to fall asleep so you warm up

the periphery to release the blood from the core and you cool down well the reason that they use cold hand and face washing was because that's this vascular surface it's the place where we can modulate temperature quite quickly the cold water on the face and the hands therefore caused Vaso constriction the the vessels and the capillaries there they all scrunched up and they force the blood back down into the core of the body so the core body temperature increase a little bit now you also get a bit of an adrenaline shot when you're splashing very

cold water on your hands and your face so there's some of that too but that's the justification so what they find firstly they were measuring different aspects of your cognition and your mood and your sleepiness those were the outcome measures to assess how did these five different experimental groups change and you can imag I mean this is I don't think I would ever take on a study where I'm doing five nap groups all within one study it's bloody amazing so they did the nonap group and then compared to the nonap group The Nap group got

a wonderful benefit just as we described and they showed benefits in their alertness in their cognitive performance and also they showed a reduction in their sleepiness so Point number one on the scoreboard for a nap then they did the nap plus the caffeine and sure enough you got an added benefit to that which you already obtained from the nap now it was nowhere near as sizable as the benefit from the nap so the addition of caffeine does give you some nice benefits and I've used this before when I've worked with sort of professional athletes we

do instigate these nap um these caffeine naps when needed so it did give a nice benefit but then when they looked at the nap Plus Cold hand and face washing and the nap plus the bright light those also added something to The Nap benefit now they didn't do the sixth Group which is really what I'm going to do some hand waving about which is the full St stack full fat method where they said okay you're going to do nap plus caffeine Plus Cold hand and face washing plus bright light but if you were to put

those together my thought is that they're probably additive rather than simply just you know netting each other out which means that if you really want to not just do a nap or a nap plus which would be the the Caffe nap but the nap plus plus version you can lean into this study and the protocol there would be you get into bed you have your espresso shot before you turn the light you Swig it go down set your alarm for 20 minutes you wake up the caffeine is kicking in you get over the inertia you

go straight out cold hands cold face by way of cold water and then you get immediate daylight for 5 to 10 minutes outside and at that point you're really in a supercharged state so that's if you just because I know there's probably going to be some audience members who are willing to give this a try or who really want to optimize don't give me you know what is good give me the extreme very best that's the only suggestion I would have based on that data I love it and actually what you just described could easily

be um translocated to the uh the period after uh waking from the nightly bout of sleep although one wouldn't ingest caffeine prior to waking up for obvious reasons um but it would make good sense to me to uh wake up obviously get sunlight in one's eyes um splash some cold water in one's face or hands or get cold shower cold plunge um caffeine or delay caffeine I mean it's essentially the same set of tools and I think it really um points to the fact that circadian rhythm clearance of adenosine uh temperature modulation and of course

the the way in which these interact um are really the the levers and and knobs to to modulate wakefulness yeah it's it's so it there are I think we've gone over this notion of naps but there are ways that you can try to manipulate the nap system still and there are ways that you can manipulate it even further but I like what you're saying because it just comes back to the fundamentals let's let's forego the the nap conversation just go back to the morning routine you're absolutely right and think about the cold water and warmart

my guess is that very few people when they go to bed they wash their face and their hands maybe they're probably not washing it with cold water before they go to bed correct they're going to be washing it with warm water why don't they do that and they just say well why would I Splash cold water on my face you know probably wakes me up you ever thought about why it wakes you up part of it is the you know the shot of activation but the other part is Thermo regulation and the opposite is what

what you want to do if anything you want to be warming your hands and your feet and that's exactly what you've always done you've always medicated your sleep onset by using warm water on your face and your hands several times during today's discussion we talked about polyphasic sleep um and the different types of polyphasic sleep that we covered are I wouldn't say conventional but they're um conventional is what are some of the more um esoteric or let's call them high performance Pol polyphasic uh strategies uh for sleep so we've spoken about polyphasic sleep in the

natural way it occurs which is during infancy and sleeping like a baby means that you're sleeping in a highly polyphasic way but probably around about the late 1990s 2000s with the emergence of the biohacker movement and the Quantified self-movement there started to become a lot of chatter online about this notion of polyphasic sleep and here no longer are we infants we're now adults but we're engaging in a pattern that is highly polyphasic polyphasic sleep simply by definition again means that you're having multiple phases of sleep within a 24-hour period And there are different strategies so

the way polyphasic sleep in adults works is that you take the 24-hour period and you think about it like a pie chart and then you start to slice that pie up into these quadrants when it comes to polyphasic sleep the goal is to put insert multiple phases of sleep around the 24-hour clock rather than one single phase but the thinness of those slices of the pie are very thin leaving large thick slices of wakefulness in between the notion that being that if you were to sort of just intersperse Little soupson of sleep in terms of

these little thin slices of sleep you can increase the amount of time that you're awake and you can increase all of the benefits of a wake so if you look at the there is a website I think it's called the polyphasic society and there it's not a scientific Society like the you know psychological the American Association for uh psychology or medical um American Medical Association or British medic it's not one of those ratified certified scientific or medical it's just society that lives online which is great and they make claims to suggest that polyphasic sleep can

improve aspects of your mood it can improve aspects of your productivity it can maybe even improve aspects of Health I think sometimes there are claims that it can help with lifespan and there are a number of different schedules that they will describe to you and that you can find out there of polyphasic sleep there is is the first one that probably people have heard of is called the uberman schedule and by the way there is no h at the start of that it is simply you I know it's not this man sitting across from me

who has anything to do with this schedule and after we discuss the data he will um reassert that very same fact then there's something called the Everyman shedule and then there is the triphasic schedule and there's lots of different other flavors of this the differences between them are in how you split up that pie chart and how much you assign to little thin slices of sleep versus longer periods of wake and how many of those you insert but they all follow the same pattern if you look at the literature however it didn't begin with the

biohacker movement the first description I can find in the human record comes from Time Magazine an issue in 1943 and they describe the protocol of at the time a fantastic very interesting designer a guy called book Minster Fuller and he created a design principle and that design principle was called the daxian principle the daxian principle was principally used initially to build unique building structures and it uses this notion of different sort of almost spokes that interconnect in a central Hub that create a self-supporting structure are the most obvious have you ever been to one of

those geodesic domes and inside you go in it's like a botanical garden and it's all tropical despite you being in a let's say being in England in London and is beautifully tropical inside of that that structure that sort of latis structure that comes in part from his Design This was the daxian principle and he scaled it to different things the daxian car the daxian house the daxian Dome it fascinating but he was no fan of sleep and he saw sleep as a rather significant waste of time when just like the rest of his daxian principle

he could be harnessing more efficiency out of the system with less structure and here less sleep structure inserted into his 24-hour period so he was the first one to describe his schedule and it was called the daxian schedule of polyphasic sleep so it may have been a practice earlier in the record but that's the earliest one I can find so let's come back to the claims of polyphasic sleep that it could improve let's say your mood or your cognition or your productivity or your health the a group of scientists at Harvard some of my old

colleagues um from Harvard they looked at all of the literature on all of the stes that were polyphasic like or testing this claim and the first thing that they found was to their claims of improved cognition productivity mood as well as health they found no supportive evidence that polyphasic sleep was helpful then they turned the tables and they said well could it be hurtful and in fact that's exactly what they found firstly the total amount of sleep that you get on any one of those schedules is decreased significantly now of course that's the goal the

quality of sleep that you get though is miserable your sleep efficiency even when you're having these short periods of time especially during the waking hours is very poor it's not a type of even short sleep that you would wish for third they found that it would reduce your REM sleep amounts so that was the first set of findings your sleep is no better if anything it's significantly worse and then they started to find that there were significant impairments in many of those things impairments in cognition in judgment making and decision- making impairment in mood and

some aspects of impairment in metabolic Health particularly glucose regulation so when it comes to polyphasic sleep sleeping like a baby if you're an adult seems to be a rather unwise piece of advice now yeah I mean it probably goes along with eating baby food drinking breast milk and um and uh having somebody else uh clothe and change you as an adult it's probably uh not advisable it doesn't seem to be at least supported by the data and again I want to be so careful here and you're very careful too I'm not here to necessarily tell

anyone absolutely how to live their life I'm just a scientist and all I can do is give you the information just as you do and then it's up to you to make the best decisions that you wish to make all I would say is that I would hope that as long as you're not hurting yourself and harming your health and you're not hurting other people then and it makes you happy then I say whatever it is in life good luck I I embrace it I always say uh do as do as you wish but know

what you're doing and don't hurt yourself or anybody else can you get me that T-shirt and I will wear it five days through Tuesday so here in this regard though I would say the evidence would suggest that maybe you're compromising your health and your Wellness but that's your choice voice and I understand it so again no judgment to the question however of as long as you're not hurting other people here I would say that there is a pause of a caution because what we know is that when you're not getting sufficient sleep I described all

of the health consequences in the first episode there's another danger here which is road traffic accidents and we describe these micro sleeps that happen and why car accidents that are caused by sleepiness can be so catastrophic there's a very interesting study that was done where they looked at people getting less than 6 hours of sleep for several nights and they put them into a driving simulator and they asked what is the probability that you have a crash or an off-road event and sleeping less than 6 hours a night resulted in a 30% increase in you

getting into a car crash now the AAA release some data showing that when you get down to 5 hours of sleep there is I think it's something like two Three Times Higher likelihood of an accident based on real data and then when you were on 4 hours of sleep it was close to a 10 times greater risk so in other words the less and less sleep that you get it's not a linear increase in your risk of a car accident it's an exponential increase so I bring this back to polyphasic sleep because I don't know

you know think about that 30% study let's not go to the extreme just less than 6 hours of sleep if this evening you call a taxi and it turns out two taxis turned up and outside of your door I said look one of these two ta you can choose either one of them but I'll just tell you that one of these taxis has a 30% higher likelihood of getting in a crash relative to the other and it's this one on the right which would you like to pick which would you like to put your wife

and children in to S it's very obvious so I rais that question just to be mindful no one would wish to cause harm on someone else to C carry the harm of someone else by way of your own doing on your shoulders for the rest of your life is not one I would wish for and it's not one that you would wish for that's the only cautionary note but other than that I would say you know sort of live life to the full well that brings us to the conclusion of yet another incredible Voyage into

the landscape of sleep most notably on the different phases monophasic biphasic and polyphasic sleep and naps and caffeine and all of their interactions these are such important topics at the level of Concepts the level of mechanisms and as you've also beautifully described at the level of protocols that is actionable tools that people can apply so thank you ever so much Matt for taking us even further along this Voyage I'll just remind people that episodes one and two of this series that U Matt is uh so generously providing information about sleep for us are out and

those can be accessed through links in the show note captions um those fill in yet other mechanisms and aspects of sleep and I'm also particularly excited for the fourth installment in this series coming up about the relationship between sleep memory and creativity so just incredibly important topics relevant to everybody I also just want to make note that I really appreciate you highlighting some of the develop velopmental shifts that occur with sleep I often get questions about um you know sleep in children and babies and uh elderly adults as well as um all the ages in

between and you've just um built this incredible tapestry of of information for people to think about and act upon should they choose so thank you Matt ever so much and I look forward to episode four Andrew thank you it is such a privilege and it remains just my absolute Delight to be here with you thank you thank you for joining me for today's episode with Dr Matthew Walker to learn more about Dr Walker's research and to learn more about his book and his social media handles please see the links in our show note captions if

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put those in the comment section on YouTube I do read all the comments on many episodes of The hubman Lab podcast we discuss supplements while supplements aren't necessary for everybody many people derive tremendous benefit from them for things like improving sleep for hormone support and for Focus to learn more about the supplements discussed on the hubman LA podcast go to live momentous spelled o us that's Liv mous.com huberman if you're if you're not already following me on social media I'm hubman lab on all social media platforms so that's Instagram X LinkedIn Facebook and threads and

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