Andrew Huberman: Sleep, Dreams, Creativity, Fasting, and Neuroplasticity | Lex Fridman Podcast #164

Lex Fridman 0:00 The following is a conversation with Andrew Huberman, his second time on the podcast. He's a neuroscientist at Stanford, a world-class researcher and educator, and now, he has a new podcast on YouTube and all the usual places called Huberman Lab that I can't recommend highly enough. Quick mention of our sponsors, Masterclass Online Courses, Four Sigmatic Mushroom Coffee, Magic Spoon Low Carb Cereal, and BetterHelp Online Therapy. Click the sponsor links to get a discount. By the way, Masterclass is testing to see if they want to support this podcast long-term, so if you're on the fence, now is the time to sign up. And I'm pretty sure Andrew will have a neuroscience masterclass on there soon enough, though his podcast is basically a weekly masterclass in itself. As a side note, let me say that Andrew is a friend and a new collaborator. We're working on a paper together about a topic we're both really passionate about, at the intersection of neuroscience and machine learning. But that's probably many months away from being published. Still, I'm really excited about this work. He's one of the smartest and kindest people I have the pleasure of talking to on this podcast, so I hope we'll talk many more times in the future. If you enjoy this thing, subscribe on YouTube, review it on Apple Podcasts, follow on Spotify, support me on Patreon, or connect with me on Twitter @LexFridman. And now, here's my conversation with Andrew Huberman.

Lex Fridman 1:28 Why do humans need sleep? Let's, let's go with the big first question.

Andrew Huberman 1:33 Okay well, the answer I'll start with is the one that I always default to when there's a why question, which is, uh, I wasn't consulted at the design phase.

Lex Fridman 1:44 (laughs)

Andrew Huberman 1:44 So, (laughs) so, so I wriggle my way out of giving a absolute answer, right? But there's one mechanism that's very clear that's super important, which is that the longer we are awake, the more adenosine accumulates in our brain. And adenosine binds to adenosine receptors, no surprise there, and it creates the feeling of sleepiness, independent of time of day or night. So, there are two mechanisms. One is we get sleepy as adenosine accumulates. The longer we've been awake, the more adenosine has accumulated in our system. But how sleepy we get for a given amount of adenosine depends on where we are in this so-called circadian cycle. And the circadian cycle is just this very, very well-conserved oscillation. It's a temperature oscillation, where you go from a low point, typically if you're awake during the day and you're asleep at night, you'll, your lowest temperature point will be like 3:00 AM, 4:00 AM, and then your temperature will start to creep up as you wake up in the morning, and then it'll peak in the late afternoon, and then it'll start to drop again toward the evening and then you get s- sleep again. That oscillation in temperature takes 24 hours, plus or mi-

Lex Fridman 3:03 Body temperature.

Andrew Huberman 3:04 Yeah, plus or minus an hour. And it, I don't... Even though I wasn't consulted at the design phase, I do not think it's a coincidence that it's aligned to the 24-hour spin of the Earth on its axis, and the fact that we tend to be bathed in sunlight for a portion of that spin, and in darkness for the other portion of that spin. So there are two mechanisms, the adenosine accumulation and the circadian time point that we happen to be at. And those converge to create a sense of sleepiness or wakefulness. The simple way to reveal these two mechanisms, to uncouple them, is stay up for 24 hours, and you will find that even though you've been... Let's say you stay up midnight, 2:00 AM, 3:00 AM, provided you're on a regular schedule, like that I follow, not like the kind that you follow.

Lex Fridman 3:50 Yep.

Andrew Huberman 3:51 Uh, you get, I will get very sleepy around 3:00, 4:00 AM, but then around 5:00 or 6:00 or 7:00 AM, which is my normal wake-up time, I'll start to feel more alert even though adenosine has been accumulating further. So adenosine is higher for me the longer I stay up, and yet I feel more alert than I did a few hours ago, and that's because these are two interacting forces. So adenosine makes you sleepy, and then just how sleepy or how awake you feel also depends on where you are in this temperature oscillation that takes 24 hours.

Lex Fridman 4:21 Okay, so that's fascinating. So there's a, a bunch of oscillations going on, and then they kind of, through the evolutionary process, have evolved to all be aligned somewhat, and they interplay. So it's, you said your, your body temperature goes up and down.

Andrew Huberman 4:35 Mm-hmm.

Lex Fridman 4:36 There's chemicals in your brain that, uh, oscillate, and then there's the actual oscillation of the, the, the- s- sun in the, in the sky. So, all of that together has some impact on each other, and somehow that all results in us wanting to go to sleep every night.

Andrew Huberman 4:57 Right. So, um, and we can get right into the meat of this, although I guess we just dove right in, but the... So the, the temperature oscillation is the effector of the circadian clock. So every cell in our body has a 24-hour rhythm that's dictated by genes like CLOCK, PER, BMAL. This is one of the great successes of biology, they gave a Nobel Prize to Reppert and ar-... I don't know if Reppert got it, forgive me, but sorry. If you got it, Steve, congratulations. If you didn't, I'm sorry, I wasn't on the committee.

Lex Fridman 5:24 (laughs)

Andrew Huberman 5:24 Um, nonetheless, did beautiful work, Steve Reppert and, and others. Um, but Mike Rosbash and, like, other people di-... worked out these mechanisms. In flies and bacteria and mammals, there are these genes that create 24-hour oscillations in gene expression, et cetera, in every cell of our body. But what aligns those is a signal from the master circadian clock, which sits right above the roof of the mouth called the suprachiasmatic nucleus, and that clock synchronizes all the clocks of the body to this general temperature rhythm by way of controlling systemic temperature, which makes perfect sense. If you wanna create a, a general oscillation in all the tissues and organs of the body, use temperature. And so, that work on temperature, if people wanna explore it further, was Joe Takahashi, who was at Northwestern, now at UT Southwestern...... Southwestern in Dallas, and it is absolutely clear that humans do better on a diurnal schedule, sorry Lex, than a nocturnal schedule, because you could say, "Well, provided I sleep and push adenosine back downhill," which is what happens when we sleep, adenosine is then reduced, "and provided I am on more or less a 24-hour schedule, why should it matter that I'm awake when the sun's out and, um, and I'm asleep when the sun is down?" But it, it turns out that if you look at health metrics, people that are strictly nocturnal do far worse on immune function, on metabolic function, et cetera, than people who are diurnal, who are awake during the daytime. And animals that are nocturnal, it's the opposite, and animals that are so-called crepuscular, which tend to be active at dawn and at dusk.

Lex Fridman 6:59 Mm-hmm.

Andrew Huberman 6:59 There's a beautiful system, I won't go down that rabbit hole, but these are animals whose visual systems operate best, they tend to be predators like mountain lions. They have optimized their waking times for the times when the animals they eat can't see well in those light conditions, but given the rod-cone ratios in their eyes, the, the mountain lion is picking o- It's like when you see, uh, special forces and they're looking through night vision goggles, and they have a clear advantage.

Lex Fridman 7:26 Mm-hmm.

Andrew Huberman 7:26 Right? They're seeing in the dark. That's basically what it's like to be a mountain lion as opposed to a bunny rabbit.

Lex Fridman 7:33 Would you say that a lot of these cycles evolved in the predator-prey relationships of the different... Throughout the food chain? So it's basically all... Somehow has to do with survival in the, in this complicated web of predators and prey?

Andrew Huberman 7:47 Almost certainly. The- there had to have been a time in which humans being awake and active at night as opposed to during the day, uh, led to high level... Higher levels of lethality, and pr- probably particular in kids. Can you imagine kids running around in the dark and getting-

Lex Fridman 8:02 Yeah.

Andrew Huberman 8:02 ... where there are a lot of animals that can see really well under those conditions and humans can't, and this would be all pre-electricity. Even if you're carrying a torch, I mean, the range of illumination on a torch is nothing compared to what, um, a, a nighttime predator like a large cat or something can, can do. I mean, they basically... They can see everything they need to in order to eat us.

Lex Fridman 8:22 Mm-hmm.

Andrew Huberman 8:22 And not the other way around.

Lex Fridman 8:24 So, o- one fascinating thing you said is, uh... That blew my mind and we went right past it, uh, which is that temperature is a really powerful... Like, if you were to think about the ways that different parts of the body, different systems in the, in the body would communicate with each other, temperature would be a really good one. And that just... I mean, maybe it's obvious, but it kind of blew my mind just now that, yeah, these systems are all distributed.

Andrew Huberman 8:55 Right.

Lex Fridman 8:56 (laughs) And they have to kind of... They're not actually sending signals, but they're coordinating. They need some sort of universal thing to look at in order to coordinate, and temperature is a nice one to, to, uh, to build around, and that way you can control the behavior of all these different systems by controlling the temperature.

Andrew Huberman 9:17 Right. It, it's attractive to think of a mechanism where the s- master circadian clock secretes a peptide or something that goes and locks to receptors in all the cells and gets it just right, but that leaves far too much room for variability, binding affinities. Cells in a lot of parts of our body are at different stages of maturation, they're turning over, liver cells and so forth. And for instance, our... We have a clock in our gut and in our liver, such that if we were to just take out your liver and put it on a table and just look at the expression of these genes, it would be in a 24-hour oscillation on its own. It's independent. But something has to entrain them and keep them all synchronized, and so it's not obvious that it would be temperature. Takahashi's great gift to biology was to show that all the stuff coming out of this master circadian clock, at the end of the day... That's a weird statement, no pun intended.

Lex Fridman 10:06 (laughs)

Andrew Huberman 10:07 At the... (laughs) At the end of the day and the night, at, at the, um, at the end of the story, it all boils down to making sure that the temperature of tissues oscillates in the same fashion.

Lex Fridman 10:16 That's blowing my mind. I'm thinking like what o- other mechanism could possibly exist to create that kind of oscillation.

Andrew Huberman 10:23 Well, in h- You're, you're Russian, it's cold in Russia for a lot of the year. The hibernation signal in certain animals is a remarkable signal. There are peptides secreted from this very same clock, that in animals like ground squirrels or bears, they go into a kind of a torpor where everything, reproduction, metabolism, everything is reduced while they're in their cave. They don't actually stay asleep all of winter. That's a myth. Um, and they actually do these very, um, dramatic and periodic arousals from hibernation where they just shake and shake and shake, it looks like a seizure, and then they go back under into the torpor. That's from a peptide that's released, but that's different because that's about shutting down the whole system. It's clear that having these very regular oscillations every 24 hours is essential for everything from metabolism to reproduction.

Lex Fridman 11:13 Is there, uh, an optimal temperature for sleep that... I, I should mention, I think your latest episode, uh, you, uh... And people should go check out helixsleep.com/huberman to support Andrew, uh...

Andrew Huberman 11:29 Thanks for the plug. (laughs)

Lex Fridman 11:31 (laughs) Uh, I mean, the amazing thing about the stuff that you create... And, oh, and yes, you have a new podcast. That's amazing, and this past month you did a whole series on sleep, which, uh, people should definitely check out. There's some podcasts that come out, uh, that just make me want to be a better human being by just the quality. Uh, 3 Blue 1 Brown, Grant Sanderson is like that for me. Just like, wow, this is, uh, education at its best. So Andrew, uh, symbolizes that and captures that brilliantly, so go support the sponsor so he doesn't stop doing the thing. Uh, so they... I think they have a cooling pad too, so I... Uh, the Eight Sleep Mattress, uh, sponsors me. Uh, they've been...... they sent me a mattress and it's been, I've never, listen, I used to sleep m- m- on the floor, not-

Andrew Huberman 12:23 Sleep where you fall.

Lex Fridman 12:24 ... s- sleep where I fall.

Andrew Huberman 12:25 Yeah.

Lex Fridman 12:25 I don't give a shit. Eh, it doesn't, doesn't really matter, but, so like, I would've never bought a, a nice mattress. (laughs) 'Cause it's like why? I'm fine, this is a floor, it's fine. Uh, but it was a game changer to, uh, be able to control temperature. Like, for me it's cooling.

Andrew Huberman 12:42 Mm-hmm.

Lex Fridman 12:42 To cool, eh, I don't know what the hell it is.

Andrew Huberman 12:44 Well, you want the brain and nervous system and rest of the body needs to drop by about anywhere from two to three degrees in order to get into your deepest sleep and transition to sleep. That's really gonna help. You don't wanna be cold that you're bothered and can't fall asleep, but that's why some people like it really cold in the room and under a warm blanket, or with socks on for some people. That can, that can be good, because this temperature oscillation is such that as your temperature is dropping, that correlates with the, generally with the most sleepy phase of your circadian cycle. So cool is better for falling and staying asleep and sleeping deeply.

Lex Fridman 13:20 And then I, I guess like that's what Eight Sleep showed, they have like an app is, uh, it warms back up, uh, to wake you up. The idea that, I haven't actually used it, I'm like, "This is stupid." Uh, i- uh, people say it works, but, uh, just keep it the same temperature throughout the night. But, uh, uh, warming it up, I guess wakes you up, which is f- which is fascinating.

Andrew Huberman 13:42 Mm-hmm. Yeah, because you're, the wake-up signal is it, it's interesting to think about, it's not just correlated with an increase in body temperature, the increase in body temperature is triggering the release of cortisol from your adrenals, and that's the wake-up signal.

Lex Fridman 13:55 Do you think it's absolute temperatures we're talking about, or is it just even relative? Just even just the decrease?

Andrew Huberman 14:00 Well, everyone's gonna have slightly different basal temperature. The idea that everybody should be 98.6, I mean, that's a myth. And there are theories that body temperature overall has been dropping in the last 50 years or so. I, I, I doubt that's true for somebody who is athletic, like you, and is, uh, you know, young and healthy. But basically, the, the coldest period of that 24-hour cycle is when you are going to be sleepiest. There's actually a period within that 24-hour cycle, it's a, it's a timepoint called your temperature minimum, and your temperature minimum tends to be about two hours before your typical wake-up time. I'm not talking about the wake-up time in the middle of the night where you go use the bathroom, or where you set an alarm to go catch a flight. I mean, if you were to just allow yourself to sleep without a clock for a few days, measure when you typically wake up, two hours before then is your temperature minimum. And that temperature minimum turns out to be a very important landmark in your circadian cycle, because it turns out that if you get bright light in your eyes in the hours immediately before your temperature minimum, so two to four hours, or any time within the two or four hour window before that temperature minimum, you are going to what's called delay your circadian clock. The next day...

Lex Fridman 15:15 Mm-hmm.

Andrew Huberman 15:15 ... that whole oscillation is gonna move forward, it'll make you wanna go to sleep later and wake up later. Whereas if you get bright light in your eyes in the hours after that temperature minimum, so let's say for me, t- typical wake-up time is 6:00 AM, my temperature minimum's somewhere around 4:00 AM. If I get bright light in my eyes 5:00 AM, 6:00 AM, 7:00 AM, it's going to advance that oscillation, so that I'll wanna go to bed earlier and wake up earlier the subsequent nights. So you might say, "Wait, but most nights I go to sleep and wake up at more or less the same time. Why is that?" And that's because the same thing is happening on both sides, you are both advancing your clock a little bit and pro- assuming that you're looking at light in the evening, you're also delaying your clock a little bit. So you get kinda captured in between, and then your rhythm more or less oscillates at the, at the same period, as we say, as the spin of the earth. Unless you're like you, where you're-

Lex Fridman 16:06 Yes.

Andrew Huberman 16:07 ... I get text messages from you sometimes at odd hours and I'm, I, if you're on the East Coast, then I know that you had to have been pulling basically an all-nighter.

Lex Fridman 16:15 Yeah, yeah. Well, th- that's the interesting, uh, point about the messiness of sleep. So most people seem to op- perform the best when they have like a regular sleep schedule. I perhaps am the same, but I don't know that. And I tend to believe that you can also perform relatively optimally with chaos of sleep, of, uh, um, like a, a weird soup of like power naps and all-nighters and all of that. As long as you're like happy. (laughs)

Andrew Huberman 16:53 Mm-hmm.

Lex Fridman 16:54 Doing what you love.

Andrew Huberman 16:55 Mm-hmm.

Lex Fridman 16:56 And may- maybe you can, um, tell me what you think about this. So I, I tend to, for myself, try to minimize stress in life. So what I found for myself with diet, with sleep, is that if I obsess about it being perfect, then I'll actually stress quite a bit when it's not. Like, I'll feel shitty, uh, when I don't get enough sleep because I know I should be getting more sleep, as opposed to the actual physiological effects of not getting enough sleep. I find if I just accept whatever the hell happens happens and smile, and just, uh, you know, take it all in, like David Goggins style, like if it sucks, it's even better. Or the, uh, w- what is it? Jocko is like, "Good," or whatever he says. (laughs)

Andrew Huberman 17:47 Right. What's, I think there're t- uh, several things that you said there are important, but I, I agree that one can have a dysregulated sleep schedule and still be a happy person and productive. Me, much of my life, I've pulled all-nighters and slept weird schedules, you know, I think many people can probably relate to going to sleep, waking up four hours later, being up for an hour or two on your computer then going back to sleep and getting amazing sleep, the next day functioning.

Lex Fridman 18:12 Yeah.

Andrew Huberman 18:12 I think we've, I think it's important that people have highlighted the importance of sleep and getting enough rest. I do think it's gone too far. And now I'm editorializing a little bit, but I think that...... we've created this anxiety about sleep, that it's gon- if we don't sleep enough, we're gonna get dementia, if we don't get sleep then, uh, you know, the reproductive axis is gonna, you know, completely crash. Um, you know, there's a lot of evidence to the contrary, and as well, just based on personal experience and based on the fact that sure, there ... it may be that a solid eight hours with no in- uh, interruptions in there, or nine or ten, could do great benefit. But you can do really well if you do what you say, which is, you wake up, you don't want to start stressing about it, creating this meta-stress about sleep. Being happy it- ... is actually one of the most powerful things that you can do, not allowing yourself to go down that rabbit hole of stress, for the following reason: a lot of our fatigue is not due just to the build-up of adenosine, or time of day, the circadian thing we were talking about earlier. An additional factor is that effort is in- ... related to the release of epinephrine, of adrenaline in our brain and body. At some point, those levels get so high that we get stressed mentally, we get stressed physically, and we want to give up. There are good data published in Cell showing that that signal, the epinephrine signal, is- eventually accumulates and there's a- a quit point. Dopamine, the molecule of pursuit and reward and feeling good, resets our ability to be in effort. In fact, a lot of people don't know this, but dopamine is actually what e- epinephrine is made from. If you look at the biochemical cascade, it starts with tyrosine, which is rich in re- ... found in red meats and things of that sort. And tyrosine is eventually converted through things like L-DOPA into dopamine. Dopamine is made into epinephrine. So h- ... I mean this sounds kind of new agey, but happiness, joy and pleasure in what you're doing creates a chemical milieu that provides more of the chemicals that allow for effort.

Lex Fridman 20:22 (laughs)

Andrew Huberman 20:22 And there's nothing new agey about that, it's in every biochemistry textbook.

Lex Fridman 20:25 Yeah.

Andrew Huberman 20:26 It's in every decent neuroscience textbook. They just don't talk about the happiness part, they just talk about the dopamine part. So I think that limiting your stress and at least recognizing, okay, if you're pulling an all-nighter or you're somehow on messed up sleep, that there is going to be a point in that 24-hour cycle where your brain is not trustworthy, where your mental state is not worth placing too much weight on because you are near that temperature minimum. And near that temperature minimum, which is ... correlates to that two-hour ... about two hours before you would normally wake up, the brain is- is hobbling along, and anything you feel or think at that time should not be given too much value. But if you can trick yourself into thinking that's the pleasure point, you afford yourself a huge advantage. There's a study done by a colleague of mine at Stanford that showed that positive anticipation about the next day events actually is a powerful metric for creating quality sleep even if the sleep is very reduced.

Lex Fridman 21:31 Mm-hmm.

Andrew Huberman 21:31 And- and you'll love this one, and I- I- ... a lot of people are gonna, you know, might be critical of this, so I just want to make sure that ... So this was work done out of Harvard Medical, it was, um, uh, Bob Stickgold's lab and Emily Hoglan did a study that showed, looking at O-chem ... performance on O-chem scores. Okay, so organic chemistry at Harvard was a pretty tough subject-

Lex Fridman 21:51 Yeah.

Andrew Huberman 21:51 ... highly motivated. G- ... A number of very good control groups in this study. What she showed was that consistency of total sleep duration was far more important for performance on these exams than total sleep duration itself.

Lex Fridman 22:06 Mm-hmm.

Andrew Huberman 22:06 So it's not that just getting more sleep allows you to perform better. Consistently getting about the same amount of sleep is more- ... is better for performance, at least in ... on O-chem-

Lex Fridman 22:17 Yeah.

Andrew Huberman 22:17 ... than just getting

Andrew Huberman 22:19 more.

Lex Fridman 22:19 That's interesting. So that's referring to more that there should be a consistent habit-

Andrew Huberman 22:25 Yeah.

Lex Fridman 22:25 ... versus, uh, the total amount. The- ... To- to me like the entirety of the picture of sleep is, uh, it's similar to nutrition in that it feels like it's ... there's so many variables involved and it's so person-specific. So, you know, a lot of studies, I mean this is the way of science, has to look in aggregate the effects on sleep. It doesn't focus on high performers, ind- ... which are individuals ultimately. Like, the question isn't ... Uh, so it's a very important question is like what kind of diet fights obesity? Re- reduces obesity? It's another question, what kind of diet allows David Goggins to be the best version of himself? So these high performers in different avenues. And the same thing with sleep, like people that tell me that I should get eight hours of sleep, it's like, uh, it- it's ... I- I mean I- I get it and they may be right but they may be very wrong, and-

Andrew Huberman 23:26 There's no evidence that eight is better than six, that you could very well do better on six than on eight. There are few other things that, um, turn out to be strong parameters for success in this domain. For instance, your entire life, waking or asleep, is broken up into these 90-minute ultradian cycles. If you look at ability to attend or do math problems or do anything, you know, drive, performance tends to ramp up slowly within a 90-minute cycle peak and then come down at the end of that 90-minute cycle, and in sleep we go through these stage one, two, three, four REM, et cetera, talk more about that if you like, those ... on 90-minute ultradian cycles as well. Ending your sleep after a 90-minute cycle at the- at the near the end of a 90-minute cycle, say at the end of six hours, in many cases is better for you than sleeping an additional hour, seven hours and waking up-

Lex Fridman 24:17 Mm-hmm.

Andrew Huberman 24:17 ... in the middle of an ultradian cycle. And there are a few apps that can measure this based on body movements and things like that, that s- ... have you- ... your alarm go off at the end of an ultradian cycle.

Lex Fridman 24:27 Yeah, yeah.

Andrew Huberman 24:27 And if you wake up in the middle of an ultradian cycle, sometimes, not always, you can be very groggy for a long period of time. I certainly do better on six hours than I do on seven. I happen to like an eight-hour sleep, it feels great. But I haven't slept an entire eight hours without waking up in the middle of the night at some point in-I don't know, forever. I c- I can't remember, it's probably some point in infancy but... And I function well during the day. I think that, that's a big...

Andrew Huberman 24:56 that's an important parameter is, how do you feel during the day? Almost everybody experiences some sort of dip in energy in the late afternoon or what would correlate to their temperature peak, and that's a good time of day to get either a 90, 90 minute or less nap. Or if you're not a napper or you can't nap, feet elevated has been shown to be good for clear out of some of this, um, the glymphatic system is this kind of like sewer system of the brain that you can clear stuff out, so legs elevated. Or one thing that I've, um, I'm a big proponent of and that my lab has been studying is what I, I now call NSDR, non-sleep deep rest, and this is just lying down. There are some scripts that we're gonna put out there soon as a, as a free resource. There are some hypnosis scripts that my colleague David Spiegel has put out there as a free resource. But non-sleep deep rest is allowing your system to drop into states of, of real calm that allow you to get better at falling asleep later, and they can be very restorative for cognitive and motor function. There's at least one study, um, out of Denmark that shows that the basal, the basal ganglia, which is an area of the brain that's involved with motor planning and action, one of these 20-minute non-sleep deep rest protocols resets levels of neuromodulators like dopamine in the basal ganglia to the same levels that they were right after a long night's sleep. So I also respectfully, uh, or semi-respectfully disagree with the idea that you can't recover lost sleep. What does that mean? I mean, th- there's no IRS for sleep, so w- what does it mean to be in debt for sleep? If you're falling asleep during the day and you're sleepy, like you're falling asleep, that's a good sign of insomnia. It means you're not sleeping enough at night. If you're fatigued during the day but you're not falling asleep, so you're just exhausted but you're not finding yourself falling asleep in meetings and in conversation, then chances are you're fatiguing your system through something else like a long run in the middle of the night-

Lex Fridman 26:52 Yeah, yeah.

Andrew Huberman 26:52 ... in Boston or whatever it is that you're up to lately at, uh, 3:00 AM.

Lex Fridman 26:55 Yes. There is a magic to the nap and (sighs) and maybe you could speak to the... 'c- 'cause you mentioned these protocols that, that don't necessarily r- it doesn't... so they're non-sleep. But to me, the nap, one or two a day, can... almost irrespective of how much sleep I get the night before, uh, have a fundamental change in my mood, in my performance-

Andrew Huberman 27:22 For the better or for the worse?

Lex Fridman 27:23 For the better, for the better.

Andrew Huberman 27:24 Yeah, likewise.

Lex Fridman 27:25 So, uh, I do tend to kind of experiment with durations. It's c- it's consistently surprising to me how like a nap of like 10 minutes... (laughs) I don't know, maybe you can speak to the perfect duration of a nap, but I find that it's like magic that a short nap does as much good and often better than a longer one, for me, for me subjectively.

Andrew Huberman 27:50 What would be a longer one? Longer than 90 minutes?

Lex Fridman 27:53 Uh, d- no, no, like 90 minutes, or bit longer than 90 min- like two hours.

Andrew Huberman 27:57 Yeah, that's dropping you, starting to drop you into REM sleep and even if it's a tiny amount of REM sleep, people can come out of those naps kind of disoriented.

Lex Fridman 28:04 Right.

Andrew Huberman 28:04 I mean, remember, in sleep, space and time are, are totally uncoupled and so they... that's an odd state to re-enter the world in if you're not gonna stay there for a while like for a good night's sleep. I think a 20-minute nap is pretty fantastic.

Lex Fridman 28:19 Would you say that's the op-... if you were to recommend to the general u- it's w- it's very weird to recommend anything to the general populace because obviously it's very person-specific, but what's a good one will you say to friends? Is 20 minutes a good power nap?

Andrew Huberman 28:32 20 or 30 minutes, 20 or 30 minutes 'cause you're going... unless you're sleep deprived, you're going to stay out of REM sleep, rapid eye movement sleep. If you're sleep deprived, you'll drop right into it. If you've ever traveled and you're really jet-lagged, you go to the hotel, you lay down for one second, all of a sudden you're just like fffroooom, you're, you're in a psychedelic dream, um, which can be pretty great too.

Lex Fridman 28:54 (laughs)

Andrew Huberman 28:54 Um, but I think that, uh, 20, 30 minutes and if you can't sleep, some people have trouble napping, then learning to relax the body as much as possible by trying to remove all expression from your face completely, letting your body kind of float. If people have h- hard time relaxing when they're awake, um, there's some terrific, uh, clinically and research tested hypnosis protocols that we could provide links to that are cost-free and that teach you how to just completely release the alertness button and you just start drifting. Now the problem is, if you don't have a, an alarm or something to go off, you... The other day I did one and I- I'm almost embarrassed to say this but there's a component of it where you actually are supposed to let your hand float up because it's a hip- hypnosis script-

Lex Fridman 29:40 Mm-hmm.

Andrew Huberman 29:40 ... so they... It's my colleague David Spiegel in the script he says, um, "Let your hand float up." I woke up an hour later and my hand was still floating.

Lex Fridman 29:48 Oh, wow, that's awesome.

Andrew Huberman 29:49 Yeah, and I was, and I was completely relaxed. So hypnosis is-

Lex Fridman 29:54 (laughs) That's awesome.

Andrew Huberman 29:54 Hypnosis is just a matter of going deep relaxation, narrowing of context, and it's all self-imposed. A lot of people think that hypnosis is like the stage thing with the pendant-

Lex Fridman 30:02 Mm-hmm.

Andrew Huberman 30:02 ... and the chicken, you know, people b- clucking like chickens-

Lex Fridman 30:05 Yeah.

Andrew Huberman 30:05 ... but-

Lex Fridman 30:06 You can do it yourself.

Andrew Huberman 30:06 ... real hypnosis is self-hypnosis. You're learning to... it involves some shifts in the way that you... the, the hypnotic induction involves looking up, closing your eyes slowly, deep breath and then imagining yourself floating. And s- people vary on a scale of about one to four, four being the m- most easily hypnotized. There are a few people who it's very hard for them to allow themselves to, to go into these states but for most people they just, they're gone. And it's nice if, if you can have access to those states because when you come out of it, you feel amazing. You feel like you slept the whole night, at least most people report that.

Lex Fridman 30:42 So refreshed,

Lex Fridman 30:43 alert.

Andrew Huberman 30:43 Ready to go. I mean basically-

Lex Fridman 30:45 Ready to go.

Andrew Huberman 30:45 ... you're ready... uh, yeah, I know you have this, um, interesting challenge coming up and I'm-

Lex Fridman 30:49 Yeah.

Andrew Huberman 30:49 ... curious what you're gonna do to reset in the hours. It... the, the frequency of running is, um, every four hours. It's not gonna allow you to get any more than a couple of hours sleep in between.

Lex Fridman 30:59 A couple of hours. So we should, we should tell it to people. I'd be curious to get your thoughts and advice on that. I'm a...... on March 5th, running 48 miles with Mr. David Goggins. So four miles every four hours, and people should join us. He's, uh, that madman is going to be live on Instagram, starting at 8:00 PM Pacific on March 5th. So-

Andrew Huberman 31:23 You're gonna join him in person?

Lex Fridman 31:25 In person.

Andrew Huberman 31:26 Undisclosed location.

Lex Fridman 31:27 Undisclosed location.

Andrew Huberman 31:28 So you're going (laughs) -

Lex Fridman 31:29 And I was, I was trying to clarify like, "Okay, so we're gonna..." Like, there'll be like friendly people around or something. No, it's just me and him by-

Andrew Huberman 31:37 Friendly people?

Lex Fridman 31:38 I don't know.

Andrew Huberman 31:39 (laughs)

Lex Fridman 31:39 Like, I just feel it's very difficult to be with David alone in a room.

Andrew Huberman 31:45 I imagine his... I mean, I've done some work with David, his energy is infectious.

Lex Fridman 31:49 Yeah.

Andrew Huberman 31:49 I don't, I don't... That, that's an intense schedule, um, and the p- the periodicity of that, those four-hour, every four hours, four miles, means that there's no chance of catching an extended block of sleep.

Lex Fridman 32:01 So it's about three hours that you have non-exercising every time. And of course, it takes time to try to fall asleep, and there's an intensity to the whole thing, you're... I mean, it's probably impossible to get anything more than, uh, two hours of sleep if you wanted to. So the optimal thing is probably, from the sound of it, I'd be curious to see what you think, but like it's getting a few 90-minute naps.

Andrew Huberman 32:29 Well, I thought about this a bit before we met up today. So I think there are two general approaches that could work. Neither one necessarily better than the other. One would be just to hammer through the whole thing, just to get your level of alertness and adrenaline ramped up so that you don't expect yourself to sleep.

Lex Fridman 32:51 Mm-hmm.

Andrew Huberman 32:52 Uh, there are certain advantages there. One is a subjective kind of emotional advantages, which is if you can't sleep, you're not gonna be stressed about that.

Lex Fridman 32:59 Yes.

Andrew Huberman 32:59 And if you do fall asleep, it's a bonus.

Lex Fridman 33:01 Yeah.

Andrew Huberman 33:01 Provided you wake up and you don't look up and you realize David's been out running for half an hour and you're behind, right?

Lex Fridman 33:07 Yeah.

Andrew Huberman 33:07 Chances are, that's not the way it'll go, you set an alarm. So that's one approach.

Lex Fridman 33:12 Yeah.

Andrew Huberman 33:12 And, and I grabbed that from, you know, I've a couple friends who were, um, who were in the SEAL teams, and they'll say that, you know, during BUD/S there was this infamous hell week, and there's this five-hour, uh, five days, excuse me, definitely five days, of no sleep, although there is a component where they offer a nap at one particular point. And a lot of people will say that it's worse to go down for that nap and then be woken up 20 minutes later than to just stay up.

Lex Fridman 33:37 Yeah.

Andrew Huberman 33:38 So, so that's one option, let's call it the, um, full blitz hammer through option. And if you happen to fall asleep, you do.

Lex Fridman 33:45 It's a bonus, yeah.

Andrew Huberman 33:46 It's a bonus. The other one would be to really anchor in these ultradian cycles, so coming back from a run, you'll pro- unless you're thoroughly exhausted, you're probably gonna have a few minutes where you're gonna wanna stay awake, it's gonna be hard to just immediately fall asleep. And getting as much sleep as you can in the intervening periods, provided that you guys aren't posting constantly or doing something else. You also, this is a question of whether or not you wanna nourish, whether or not you wanna eat or not in that time. Anytime we put food in our gut, I don't care if it's meat or oatmeal or broccoli or cardboard, you're drawing blood into the gut, and so you are going to divert some energy towards digestion, and it's gonna make you sleepy. There's a reason why the rest and digest, the parasympathetic nervous system is called that. So, you could decide that you are only gonna sleep in certain blo- in between certain blocks. That would be another way to think about this.

Lex Fridman 34:41 So th- that mist- 'cause I did this for last year, uh, I ran very slow, some of it was walking, I was listening to audiobooks, and one of the biggest mistakes I did is to overeat during that time.

Andrew Huberman 34:53 Right.

Lex Fridman 34:54 It was, uh, it made the experience very unpleasant. So I, I have been considering basically eating almost nothing throughout the day.

Andrew Huberman 35:01 Being fasted will increase alertness because high levels of epinephrine in your system from fasting. You just think about fasting or being thirsty before you get exhausted, people always think, "If I don't eat, I'm gonna be tired." No, the, the energy that you derive from food is going to be, uh, used from glycogen and after a long storage and conversion process. So the food that you eat is going to consume energy to digest. And so a lot of people feel better fasted. And p- presumably throughout history, people have fasted for long periods of time and had to stay up for two or three days, and, you know, God forbid if a family member is sick, you can stay awake in the hospital without any trouble. So that alertness system, and it's, you know, it's all mental. Um, actually, and then there's a third, uh... So you could try and sleep or, or take care in between.

Lex Fridman 35:48 Yes.

Andrew Huberman 35:48 Yeah. And then there's a third approach.

Lex Fridman 35:50 Uh-oh. Yeah?

Andrew Huberman 35:51 But I didn't come up with it.

Lex Fridman 35:52 What, what is it?

Andrew Huberman 35:53 But David did.

Lex Fridman 35:54 Okay.

Andrew Huberman 35:54 So, uh, I actually texted him-

Lex Fridman 35:56 (laughs) Oh, no.

Andrew Huberman 35:56 ... earlier because I had a feeling that I heard that you were gonna do this challenge. So I asked David.

Lex Fridman 36:03 Oh, God.

Andrew Huberman 36:04 (laughs) So these are David Goggins' words, not mine.

Lex Fridman 36:08 Okay.

Andrew Huberman 36:09 "One."

Lex Fridman 36:11 (laughs) "Okay."

Andrew Huberman 36:12 "Being organized is super important. Two, you wanna waste as little time as possible. Three, you need to eat, sleep, and rehab in as little time as possible so you can sleep as much as possible." Oh, interesting. By the way, this is the first time I'm reading this, so.

Lex Fridman 36:27 Yeah.

Andrew Huberman 36:28 Um, "Four, meal prep and gear prep, et cetera are very important." That's, um, that's consistent with everything I know about military, they, they don't, th- they don't leave too much to chance. "Five," again, these are David's words, "All that said, he's fucked on most all that."

Lex Fridman 36:44 (laughs)

Andrew Huberman 36:45 Because he'll be interviewing me before or after. I will also be interviewing him.

Lex Fridman 36:49 Oh, shit.

Andrew Huberman 36:51 "Five, long story short, the only thing that might help is a very special pill." Ooh, this is interesting.

Lex Fridman 36:56 (laughs)

Andrew Huberman 36:57 "They are called SIU pills. Hard to get, but I believe he can get them. SIU stands for suck it up." (laughs)

Lex Fridman 37:05 (laughs)

Andrew Huberman 37:06 ... tell him to grab his balls.

Lex Fridman 37:07 Yeah?

Andrew Huberman 37:07 (laughs) He'll find those pills there. (laughs)

Lex Fridman 37:11 (laughs) That's number six? All right.

Andrew Huberman 37:13 (laughs) And then the last one-

Lex Fridman 37:14 Yeah.

Andrew Huberman 37:14 ... stay hard, brother.

Lex Fridman 37:15 Stay hard, brother. Amen. I, you know, that was one of the other things that I think makes this challenging, is that I'll be doing a podcast throughout. So first of all, I'll do a long one before and after, but also, I'll have to come up with things to talk to him about.

Andrew Huberman 37:33 Mm-hmm.

Lex Fridman 37:34 So, like, it's, it's a different thing to do something privately-

Andrew Huberman 37:39 Mm-hmm.

Lex Fridman 37:40 ... and then publicly. I know it doesn't seem that way, but like, one of the hardest, the hardest thing I had to do last time was to turn on the camera and talk to the camera, 'cause I, uh, last time I did it, I recorded, um, every single time I did a leg, I recorded something I'm grateful for. It's just kinda unrelated. I'm not a fan of, like, talking about, like, how I'm feeling or how the run is going. I wanna do something totally unrelated to the run, uh, with the run as the background, you know?

Andrew Huberman 38:12 Mm-hmm.

Lex Fridman 38:12 So sort of something I'm grateful for, or just any kind of, uh, interesting discussion.

Andrew Huberman 38:16 Gratitude, uh, I mean, uh, I hate the word "hack," like, "Oh, it's a dopamine hack," or, "It's a serotonin..." I, I don't like the word "hack" because A, it's disrespectful to hackers who do a real thing.

Lex Fridman 38:27 Yeah. (laughs)

Andrew Huberman 38:27 And B, a hack, it implies that it's some sort of trick that you're, you're, you're kinda gaming the system. You know, what, what works is mechanism, right? Biological mechanisms were designed to work, (laughs) be- and they were selected for to work under variable conditions. And as you know and I know and we have great appreciation for the fact that the nervous system was designed to be an adaptive machine, so that you don't have to sleep eight hours every night.

Lex Fridman 38:55 Yeah.

Andrew Huberman 38:55 You can do this thing. And things like gratitude allow you to tap into chemical resources, and that's not a hack. The, the fact that being grateful for something external to the event happens to release serotonin and have a certain soothing effect, or a dopamine and give you more epinephrine and let you go further, that's not a hack. That's actually what allowed the h- human machine to evolve to the point that it is now.

Lex Fridman 39:22 Mm-hmm.

Andrew Huberman 39:23 Every time, you know, an inventor eventually created something that worked and felt great about it, you can imagine that the, the first, you know, air flight felt pretty awesome and motivated those people to go on and do more. They, they didn't just go, "Oh," you know, yawn and go have a beer. So being able to access the genuine in- internal states of gratitude and reward works. You can't trick the system. You can't pretend that you're grateful for something. But if you can identify or attach yourself to some larger goal or something that's deeply gratifying to you, or place it in service to a relative that passed away that you care a lot about, that's not a hack. That's accessing the deepest components of your nervous system. And, um, to steal your kind of lingo, you know, there's real beauty there, right? (laughs)

Lex Fridman 40:13 (laughs) Yeah, but for an introvert like myself, and I think David, I don't know if he's an introvert, but like, he's not... Despite the fact that he has written a great book and he communicates, he puts himself out there, he's not really a fan of communication. He's not... I don't know if he's energized by speaking his mind.

Andrew Huberman 40:33 I don't know him well enough to know.

Lex Fridman 40:34 Like

Narrator 40:35 extensively.

Andrew Huberman 40:35 I mean, we've done a little bit of work together and, um, you know, we're in communication now and again. He's obviously super impressive. Um, I don't know. It seems that he's a pret- it seems like he's a pretty private guy.

Lex Fridman 40:44 Yeah. So like-

Andrew Huberman 40:45 Um, I, you know him, so I don't have access to that.

Lex Fridman 40:48 So for me, I'll just speak to myself, and I think David is the same, but I'll speak to myself that it was a hugely draining thing, not to experience the gratitude, experiencing the gratitude, just like you're saying, is really energizing. And it's, it's a powerful thing. It's a, it's a, it can lift up your mood. But to turn on the camera and have to use words, which is very difficult to do, to explain like what you're feeling and do it in a way that you know a bunch of people will be watching is really draining. And one of the things I'm concerned about that in this whole process, how do I keep my mind sharp while also keeping the perform- the physical performance sharp? And that's a little bit scary, because talking to David, like, actual intellectually sharp, like, thinking, being charismatic and (laughs) as much as I can be, and like being still maintaining a sense of humor too, 'cause I can be... I, I become, with sleep deprivation, with exhaustion, you start being, uh-

Andrew Huberman 41:56 The Russian bear comes out. (laughs)

Lex Fridman 41:58 ... you start being such a d- like you s- I become a David Goggins, essentially. Like...

Andrew Huberman 42:03 Oh, it makes you irritable. Sleep deprivation makes us irritable. There-

Lex Fridman 42:06 Yeah.

Andrew Huberman 42:07 There's, it's clear so that in the early part of the night, we get a higher percentage of those ultradian cycles are occupied by slow wave sleep.

Lex Fridman 42:15 Mm-hmm.

Andrew Huberman 42:15 Sometimes just called non-REM sleep. And those early night sleep bouts are great for muscular repair and for certain forms of learning, but REM sleep, the rapid eye movement sleep, which it starts to accumulate and occupy more of those 90-minute ultradian cycles toward the late part of a sleep bout, so toward, typically toward morning, um, but toward after you've been asleep a while, that's when you do the emotional processing. That's when we recover the ability to feel refreshed and not irritated by things. And if you deprive people of REM sleep, they become selectively, uh, bad at m- at uncoupling the emotion from things that happened in the previous days. So the little things start to seem like big things. I always know I'm REM sleep deprived when, um, I'm irritable and when, um, I look at like the word "the" and it doesn't look like it's spelled right and I'm kinda pissed off about it.

Lex Fridman 43:10 Yeah.

Andrew Huberman 43:10 Like, something's off. And y- we actually are s- becoming slightly, um, psychotic when we're REM sleep deprived. You're not gonna get a lot of REM sleep in this thing, except as you fatigue more, if you do fall asleep, you're gonna drop more and more into REM so that those 90-minute cycles, you won't have to go through stage one, stage two, stage three, and then REM. You're just gonna drop right into REM. So you can count on your system to compensate for you.But I think that just the knowledge that you tend to get irritable as the time goes on, just that third personing of yourself-

Lex Fridman 43:40 Yes.

Andrew Huberman 43:40 ... that awareness, the observer, that can be very beneficial because em- there may be bouts during this event when you just should probably say nothing, and maybe you just, um, I don't know, smile and record or not smile or do, do whatever it is, because you're, you're gonna be conserving energy. If it feels like a grind, that's epinephrine being released. That's epinephrine that you could devote to the physical effort. But humor is an amazing anecdote for this, because it resets that, it's that dopamine release that gives us that fresh perspective, and it's a c- it's a real chemical thing. It's not a, it's not a hack, it's not a, it's not a trick, it's not a visualization. It's biology in action.

Lex Fridman 44:22 Well, but I think the act of, uh, interviewing, of conversation in these pros- even if you don't want to do it, the right thing to do, even when you're feeling irritable, is to, to do the third person view and be able to express with words that you're feeling irritable. Like express what you're going through. Ex- you know, uh, use words, which I hate doing. I honestly, I think my ultimate thing would be just to never say a single word to David Goggins and just go through hell. It doesn't matter what we do. But to do it quietly. To also express it, that's my ultimate hell. And I think that-

Andrew Huberman 45:02 Well, he's definitely gonna be... if I know David at all, he's, he's going to try and find your buttons. Like he's gonna...

Lex Fridman 45:07 (laughs) .

Andrew Huberman 45:07 He, I mean, he, even though he knows he can complete this...

Lex Fridman 45:11 Yeah.

Andrew Huberman 45:11 ... and I, I believe that he trusts that you can complete it too. I, I believe you can, you will complete it.

Lex Fridman 45:15 Yeah. Yeah.

Andrew Huberman 45:15 You know you will complete it.

Lex Fridman 45:17 Yeah.

Andrew Huberman 45:17 Right. There's no question about that. But he's not gonna make it easier for you. He's gonna make it harder.

Lex Fridman 45:21 Well, I'm afraid, so I'm like, you know, it's very difficult for me. So 48 miles is not easy. I have not been training that much, so I'm now ramping up, but it's not like going to m- kill me. We'll see what happens. Of course, for him, he might almost get bored because I think the 48 miles for him is easy. I think not-

Andrew Huberman 45:42 I don't know that, that... I don't know that that ever gets easy. I have a friend, uh, Casey Cordial, who works with David. He's, uh, does some, um, physical, uh, rehab type stuff with him, and he took Casey on a 50 miler, and Casey said like 16 miles into it, he was just like, he had hit his wall.

Lex Fridman 46:00 Yeah. Yeah.

Andrew Huberman 46:00 But they f- he found it. They, they find it togeth- you know, you find that portal.

Andrew Huberman 46:06 There is one thing I want to mention. There's some very good physiology that can perhaps support the actual running effort part.

Lex Fridman 46:12 Mm-hmm.

Andrew Huberman 46:12 These are very new data, and we have a study going on, uh, with David Spiegel at Stanford looking at how different patterns of breathing can affect heart rate variability. Heart rate variability is good. There's this interesting mechanism, uh, that I think most people might not realize, but that medical students learn, that your breathing and your heart rate and your brain are in this really remarkable interplay. It goes like this. When you inhale, this isn't breath work, we're not gonna do breath work.

Lex Fridman 46:37 (laughs) .

Andrew Huberman 46:37 But when you inhale, the diaphragm moves down.

Lex Fridman 46:40 Yeah.

Andrew Huberman 46:42 The heart gets a little bigger 'cause there's a little more space in the thoracic cavity. And as a consequence, blood s- flows a little bit more slowly through that larger volume.

Lex Fridman 46:50 Mm-hmm.

Andrew Huberman 46:50 And there's a category of neurons, the sinoatrial node, that sees that, that recognizes that, that slower rate through that larger volume. It sends a signal to the brain stem, and the brain stem sends a signal back to the heart to speed the heart up.

Lex Fridman 47:03 Mm-hmm.

Andrew Huberman 47:04 So every time you inhale, you're d- speeding the heart up. When you exhale, the diaphragm moves up, the heart gets a little smaller, the volume is smaller, blood flows more quickly through the heart, signal sent up to the brain, and the brain sends a signal back to s- slow the heart down. This is the basis of heart rate variability. So at any point, if you feel like your heart is racing and you feel like you're working too hard per unit of effort...

Lex Fridman 47:26 Mm-hmm.

Andrew Huberman 47:27 ... focus on making your exhales longer or more intense than your inhales. If ever you feel like you're truly flagging, you do not have the energy to get up, it's like, okay, it's time to go and you're exhausted, you want to draw more oxygen into the system, get your heart rate going faster. Now, some people when they hear this probably think, well, this is really obvious, but there's so much out there about breath work and how to breathe and all this stuff, but no one talks about how to do it in real time-

Lex Fridman 47:52 Mm-hmm.

Andrew Huberman 47:52 ... while you're exerting effort.

Lex Fridman 47:53 So this is something like almost like second by second, you can adjust things to just in real time based on how you're feeling, by basing on the heart rate.

Andrew Huberman 48:03 That's right.

Lex Fridman 48:03 The experience of the heart rate.

Andrew Huberman 48:05 That's right. So one thing that w- could, could be very efficient and we, we're doing some work with athletes now, so these are unpublished data, but if you, while you're running, i- if you want to get into a nice cadence of heart rate variability, do double inhales (inhales) (exhales) (inhales) (exhales) while you're running. What this will do is that when you do the double inhale, it has the effect of, of reopening the alveoli of the lungs. Your, your lungs are filled with tons of little sacs. When you, they tend to collapse as you fatigue. When you... and carbon dioxide builds up in the bloodstream, and that's when we start getting stressed. If you've ever been sprinting and you start getting beat and you're-

Lex Fridman 48:40 Mm-hmm.

Andrew Huberman 48:40 ... going as hard as you can, what, what you really need to do is double inhale and reinflate these sacs in the lungs and then offload a lot of carbon dioxide. So when you're at a steady cadence and you're feeling good, double inhale, exhale, double inhale, exhale is a terrific way to breathe while you're in ongoing effort.

Lex Fridman 48:56 By the way, any, uh, recommendations or differences in, uh, nose or mouth breathing?

Andrew Huberman 49:03 So nasal breathing, there's a lot of excitement now obviously about nasal breathing 'cause of James Nestor's book, Breath. Um, there was also, if people are gonna know about that book, they, I do feel like out of respect for my colleagues, there was a book by Sandra, um, Kahn and Paul Ehrlich at Stanford, both professors at Stanford, with a forward by, um, Jared Diamond and Robert Sapolsky, so...

Lex Fridman 49:24 Nice.

Andrew Huberman 49:24 Some heavy hitters in this book. And the book is called Jaws: A Hidden Epidemic, and it's all about how nasal breathing is better for us, especially kids, than mou- being mouth breathers under most conditions, for sake of improving immunity, it turns out there's a microbiome in the nose, like all sorts of good stuff about nasal breathing preferentially.But when we exercise, y- you can j- you can do pure nasal breathing, but the problem is, once you get up to kind of third and fourth and fifth gear effort, you can't n- nasal breathe and be at maximum capacity, unless you've been training it for a very long time. So I would say double inhale through the nose, offload through the mouth. So double inhale, exhale while you're in steady effort, and then if you really feel like you need to gas it and you're pushing, the data show that then just use whatever's there, right? Just go into kind of default mode because bringing too much concentration to something is also going to spend epinephrine. The goal is to get into that, I don't like the word, but the flow state, where you're not thinking too much, you're just in exertion. So these are, so these are things that can help in the transitions, um, but th- I don't think there's any secret breathing technique. You know, anyone who's been in the SEAL teams will kind of, you know, they'll tell you, like, "There's no breathing technique," right? If there's a, there's tools that you can look to from time to time, and these double inhale exhales can be great for setting heart rate vari- variability in very quickly and getting into a steady cadence while you're exercising. But if there's a sprint, like if suddenly you guys are sprinting, ditch the, ditch the double inhale exhale-

Lex Fridman 50:53 Yeah.

Andrew Huberman 50:53 ... and just sprint.

Lex Fridman 50:55 One thing that you mentioned, he's probably gonna push my buttons. It's a good place to ask a question about anger. So I'll probably get pissed off at him at some point, (laughs) I'm guessing, and d- do you have thoughts from a scientific perspective, or also just a personal, philosophical perspective, about the role of anger in all of this, in, in managing alertness, performance?

Andrew Huberman 51:20 I think about this a lot because there's so much out there about how important it is to do things from a place of love.

Lex Fridman 51:27 (laughs)

Andrew Huberman 51:27 You know? (laughs) Um...

Lex Fridman 51:28 I tweet about it all the time. (laughs)

Andrew Huberman 51:30 And, and I think, and love is powerful, right?

Lex Fridman 51:32 Yeah.

Andrew Huberman 51:32 It, you know, it, it is interesting that autonomic arousal, alertness, let's just make and use simple language. Alertness physiologically looks identical for love and excitement as it does for anger and frustration and wanting to defeat your opponent, or whoever that opponent happens to be. They're identical, except that the love component does tend to be associated with the release of neurochemicals, of the serotonin and dopamine type, that do have this replenishment component. I don't think one wants to be in constant anger and friction, but, I mean, I'll come clean a bit. There have been portions of my career where some of my best work, my extra two hours, my ability to nail a, a really hard deadline or problem has come from not wanting to get out-competed, or from wanting to prove something. That l- these days, I, I, I don't, I'm not oriented f- from that place toward my work quite as often, but I think we should be really honest. Anger is powerful, uh, provided it's channeled. It's very, very powerful, and it can give you a ton of fuel and gas to push when otherwise you'd tap.

Lex Fridman 52:44 Yeah, Joe Rogan has, aside from being a fan of his, has been an inspiration to sort of be ... to have a kind of loving view on the world, in the way you approach the world, s- uh, to me. So I've tended to want to approach the world that way, but in the same way, David Goggins has been an inspiration to, like, uh, yeah, be angry at stuff and, uh, use it as fuel. Like, he almost, uh, conjures up artificial demons in his mind just so he can fight them. Uh, you know, but at the same time, I tried that 'cause I, I did a challenge in the summer of, uh, where for 30 days I was doing a lot of push-ups, and it was, uh, over time, it was counterproductive for me. Like, I found that it was easier to just, like, the roller coaster that the emotional, like, being angry at stuff takes you can also be exhausting.

Andrew Huberman 53:46 Oh, absolutely.

Lex Fridman 53:47 A- and it can take you down, like, the, the ups of it are good, but the downs are bad. And what I found is better to get, to use it as a boost every once in a while, but mostly to get lost in the, you were talking about the breath work, the ... (breathing deeply) like getting lost in the ritual of it.

Andrew Huberman 54:05 Mm-hmm.

Lex Fridman 54:05 Like the, the b- like that, as opposed to going on the big roller coasters of emotion.

Andrew Huberman 54:10 Yeah.

Andrew Huberman 54:11 This brings us into the realm of neuroendocrinology, is that there's a fascinating relationship between the hormone system and the nervous system, and, you know, hormones work, in general, on slower time scales. The definition of a hormone is something, is a chemical released at one location in the body, goes and acts at multiple locations far away i- within the body. Pheromone would be between two bodies. Neurochemicals like dopamine and serotonin tend to work a little more quickly. There are hormones like adrenaline and cortisol that can work very fast, but here I'm referring mainly to testosterone, prolactin. Prolactin tends to be, in men and women, tends to make people kind of lazy and wanna, um, take care of young, it tends to throw down body fat so we can stay up late, it's secreted in response to having children. These are all l- l- in humans and in animals. There's a very interesting relationship between testosterone and dopamine...

Lex Fridman 55:02 Mm-hmm.

Andrew Huberman 55:04 ... that speaks directly to what we're talking about now. So dopamine and testosterone are closely related in the pituitary system, and obviously pit- uh, testosterone comes from the adrenals and from the testes, but the m- the major effect of testosterone is to make effort feel good.

Lex Fridman 55:24 Mm-hmm.

Andrew Huberman 55:24 That's what testosterone does. It has other effects too, right? Reproductive effects, androgenizing parts of the body, et cetera, but it makes effort feel good. The testosterone molecule is synthesized from cholesterol. Cholesterol can either be made into cortisol, a stress hormone, or testosterone, but not both. So you have a, a limited amount of cholesterol, and it gets, uh, diverted towards stress or towards tes- or this pathway where effort feels good.

Lex Fridman 55:52 Mm-hmm.

Andrew Huberman 55:53 ... that's the pathway you wanna get into. The anger pathway, if we were to just kind of play a, a mind experiment here, the anger eventually is gonna divert more of that cholesterol molecule to cortisol and stress, and you will be slowly depleting testosterone. Now, going into this, you'll have plenty of testosterone, but after a couple days, there have been very interesting studies showing that testosterone doesn't necessarily drop with sleep deprivation. That's a bit of a myth. You need it to replenish testo- ... you need sleep to replenish testosterone eventually. But the real question is, are you enjoying what you're doing? And here the, the work was, uh, some of the major work on this was done by Duncan French, who runs the UFC Training Center. He did his PhD at UConn, um, Storrs, did a really beautiful PhD thesis sh- sh- looking at the relationship between stress hormones, testosterone, and dopamine. Really interesting work. And the, the takeaway from all of this is, if you can just convince yourself, or ideally, if you can just enjoy yourself, you are going to maintain or maybe even increase testosterone stores, which will make effort feel good. And to me, aside from neuroplasticity where everything becomes automatic after this experience, to me, that's the holy grail. When effort feels good, life just gets way better. And we're not talking about achieving the reward. I'm not talking about the end of this thing. I'm talking about the process of it feeling really good.

Lex Fridman 57:19 Yeah, the pr- you know, there is a magic to, uh... I don't know if you can comment on this, but I find myself being able to s- ... if I just say I'm feeling good, like this ho- this old hack of, like, smiling while you're running, if it, if I just tell myself, "I'm feeling really good right now," no matter how I'm actually feeling, I'll start feeling way better and the whole thing, there's a cascading effect that, uh, allows me to maximize the effort, which is, it's quite fascinating. It's like, it's weird.

Andrew Huberman 57:51 Hormones are powerful. The relationship between thoughts and hormones and these physiological things is enormous. I had a colleague that a f- a few years ago he was dying of, of pancreatic cancer, and I was interviewing him just 'cause I, he's an important figure in our community and I, he was a friend, and there was one day where he, he told me, he said, you know, "I don't wanna make it past the new year. I just..." And it was, it was crushing for me to hear, and I knew that he had been on some androgen therapy, um, for a con- for a whole set of other things, and I, I said, "You know, um, have you taken your andro- androgen cream?" And he was like, "No, I haven't done it. Go get it for me." I have this on film. He takes it, he puts the andro cream on. I'm not suggesting people take androgens, by the way.

Lex Fridman 58:33 Yeah.

Andrew Huberman 58:33 10 minutes later, he says, "You know what? I think I wanna live into the new year, and I'm gonna write 12 letters of recommendation." He went to MIT, by the way.

Lex Fridman 58:41 (laughs) .

Andrew Huberman 58:41 He said, "I'm gonna write 12 letters of recommendation," and he did. And so there's something about these molecules that in an ancient way, in all organisms, all m- mammals as far as we know, are linked to the will to live. They're linked to effort and making effort feel good, which has been fundamental to the evolution of our species. I always say, people think that the opposite of testosterone is estrogen, but it's not. The opposite of testosterone is prolactin, which makes us feel quiescent and not in pursuit of things, et cetera. Testosterone makes effort feel good. Estrogen makes emotions feel okay. (laughs) .

Lex Fridman 59:19 (laughs) . I love it.

Andrew Huberman 59:19 And, and, and, and they are in mixed amounts in, um, in a- people, as I say, of all chromosomal backgrounds.

Lex Fridman 59:26 Yeah.

Andrew Huberman 59:26 Yeah.

Lex Fridman 59:27 I mean, you also mentioned fasting potentially through this, uh, two-day thing. It'd be cool to get your thoughts about fasting in general. Do you think, uh, on a personal level and at a higher sort of level of studies that you're aware of in physiology and so on, what do you think about intermittent fasting of, like, not eating for 16 hours and then having an eight-hour window? Or something I've been doing a lot recently, which is eating only once a day, so that's 24-hour fast, I guess, one meal a day. Or something I've, um, been thinking about doing, haven't done yet of doing, like, 72 hours or some people do, like, f- uh, five-day fasts in general. So this would be, for this particular run, would be a t- uh, 48-hour fast if I don't eat at all. Uh, what do you think about that for performance, for m- mood, for all those kinds of things?

Andrew Huberman 1:00:21 I can speak a little bit to the science and a little bit of my own experience and then some anecdotes of people that have done very hard, very long duration things and what they've told me. So I just wanna make sure I'm separating those out so people know my sourcing. I think... Now, none of this is about the actual long-term nutritional benefits of one thing or the other. But if you look at the science on intermittent fasting, it's pretty remarkable. O- m- before I was at Stanford, my lab was in San Diego. One of my colleagues was Satchin Panda at the Salk. He's a phenomenal biologist and researcher, wrote a book called The Circadian Code. It's very, very good, and, and kind of popularized intermittent fasting, although there were others that had, um, talked about this before. Ori Hofmeckler talked about the warrior diet. People-

Lex Fridman 1:01:04 Mm-hmm.

Andrew Huberman 1:01:04 ... probably don't, might not know who Ori is, but he's, he's sort of the originator of the, this business of intermittent fasting, eating once a day or limited. Anyway, Satchin has published papers, peer-reviewed papers in very good journals like Cell and elsewhere showing that limiting the consumption of calories to eight, you know, four, six, or eight, or even 10 hours of every 24-hour cycle and keeping that more or less correlated with the light, with when s- the sun is out-

Lex Fridman 1:01:34 Mm-hmm.

Andrew Huberman 1:01:34 ... leads to less liver disease, improved metabolic markers, less body fat, et cetera. It, he, in the mouse studies, they even gave the mice the choice to eat whatever they wanted as much as they wanted as long as they restricted it to a certain period-

Lex Fridman 1:01:47 Mm-hmm.

Andrew Huberman 1:01:48 ... within the 24-hour cycle, they, they did great. They l- they maintained a healthy weight or even lost weight. When they took the same amount of food and they stretched it out across the 24, the entire 24-hour cycle, so this is eating every hour or two hours, the animals got fat and sick. So it's pretty remarkable data.... how much of that translates to humans isn't clear, but one thing that's really clear with humans is adherence, right? We could talk a lot about nutrition, and some of the problems with the studies on nutrition is that what people will do in a laboratory is often hard to do in the real world. Low carbohydrate diets just, they tend, because they tend to focus on foods that have high amino acid content, like meats. Generally, people are less hungry on their, those than they are on calorie-matched diets of fruits and vegetables and carbohydrates, because when the insulin goes up, you get hungry and you want to eat more.

Lex Fridman 1:02:38 Mm-hmm.

Andrew Huberman 1:02:38 So this is not a push for carnivore or a push against one thing or the other, it's just there are a lot of factors. But we know for sure that when you're fasted or when you have low amounts of carbohydrate in your system, complex carbohydrate, your alertness is gonna go up. Fasting increases, increases alertness, eh, and epinephrine for the sole purpose of getting you to go out and find food. Can you imagine if our ancestors got hungry and they were like, "Oh, I'm too tired to go find food"? We wouldn't be here, it'd be like robots or something like one of your alien, (laughs) one of your alien buddies will be like running the planet.

Lex Fridman 1:03:14 W- we can only dream.

Andrew Huberman 1:03:14 So I think that, um, if you want to be alert, fasting or keeping carb- complex carbohydrates to a minimum is very valuable. If you wanna sleep and you wanna be sleepy, ingesting foods that have a lot of tryptophan, which is the precursor to serotonin, so complex carbohydrates like rice and grains, turkey, white meats, those things do create a sense of sleepiness. However, there is a caveat, and this is one problem with the once-a-meal, once-a-day meal, is that any time you have a lot of food in the gut, you're increasing sleepiness, because you're diverting blood to the gut. It's gonna trigger the vagus to signal to the brain to shut down your system and utilize those nutrients, can, you know, digest and utilize those nutrients. So I've done the once-a-day eating thing. The problem is I eat so much in that meal that I'm exhausted. And so it doesn't always lend itself well to the schedule. But...

Lex Fridman 1:04:06 Interesting.

Andrew Huberman 1:04:06 So in a six or eight hour eating block for me is a little bit better.

Lex Fridman 1:04:09 Mm-hmm.

Andrew Huberman 1:04:10 I do eat carbohydrates. I'm probably one of the few people left on the West Coast that actually consumes carbohydrates, and will...

Lex Fridman 1:04:15 I don't know...

Andrew Huberman 1:04:15 ... say that out loud.

Lex Fridman 1:04:15 I don't know if people eat carbs anymore.

Andrew Huberman 1:04:17 (laughs)

Lex Fridman 1:04:17 That's weird.

Andrew Huberman 1:04:17 They don't.

Lex Fridman 1:04:18 Where do you even find carbs nowadays? (laughs)

Andrew Huberman 1:04:19 Where do you find... Yeah, I like oatmeal, I like rice. The, the other time is if people are doing very high intensity weight training, they need to replenish glycogen.

Lex Fridman 1:04:26 Yeah. On the alertness side, I, I do feel like it's probably person-dependent. For me, alertness, being alert makes my life better in a lot of ways more than just the alertness itself. Like, for example, one of the things I discovered with fasting is that when I was training twice a day in jujitsu, for example, and competing and so on, I performed way better at, at things that you traditionally would say you need carbs for, which is explosive movements and all that. Uh, I don't know if I actually performed better in terms of like the f- the force of the explosion, (laughs) uh-huh.

Andrew Huberman 1:05:05 Mm-hmm.

Lex Fridman 1:05:05 ... the explosiveness. What I do know is the alertness resulted in me, uh, doing the technique more precisely.

Andrew Huberman 1:05:13 That's the dopamine and epinephrine system in action. And there's a, you know, and there, there are some other just purely, uh, physical aspects to one diet versus the other that can be complicated. If you're ingesting carbohydrates, complex carbohydrates, you're going to replenish glycogen, which is great, but they also tend to be bulky and fibrous. And I don't, have never rolled jujitsu, but running when you have a lot of bulky fibrous...

Lex Fridman 1:05:37 Yeah.

Andrew Huberman 1:05:37 ... food in your, in your gut or in your intestine, it can be a barrier, it can be uncomfortable. And so some people do really well on low carbohydrate meat-rich diets because they're just not as bloated. They're not carrying as much water and other stuff, uh, carbohydrate carries a lot of water molecules with it. So there are aspects to being able to train and being really explosive 'cause you feel light. One anecdote that really, um... Again, I'm not encouraging any one particular kinda diet, but I have a friend who was in the, uh, in the SEAL teams, um, I happen to know a number of people in that community, and he told me that he did this very long fast. It was a fast that I think they, you get to eat a little bit of soup and or broth, and there's like a bar or something, but it's like a nine-day thing.

Lex Fridman 1:06:18 Mm-hmm.

Andrew Huberman 1:06:18 And he's, he's a very strong athlete, and he said that on day six or seven he was running up some hills or something while he was on deployment, and he felt amazing. He had kinda hit this other level. He was somebody who had boxed in the Naval Academy. He was somebody who was, had, he knew, knows and knew high output, and he felt like he'd discovered the, the thirteenth floor. That there was another floor to this performance space that he hadn't experienced except while he had fasted, and he said that that was a remarkable clarity of mind, energy. It's a little bit of what you described.

Lex Fridman 1:06:55 Mm-hmm.

Andrew Huberman 1:06:55 He, he described a kind of suppleness and explosiveness. So there's probably something...

Lex Fridman 1:06:59 So on which day?

Narrator 1:07:00 Uh, yeah.

Andrew Huberman 1:07:01 Uh, at once he was in the fifth or sixth day of the fast.

Lex Fridman 1:07:04 See, see, this is the thing is I've never been there, uh, on the second, third, fourth, fifth day, that kinda thing, but when I just don't eat for 20 hours, uh, many times through my training, the clarity. It's like you feel like everyone is moving super slowly...

Andrew Huberman 1:07:22 Mm-hmm.

Lex Fridman 1:07:23 ... and you're able to like dominate people you weren't able to before. It's like...

Andrew Huberman 1:07:27 Well, you might have slipped into f- or, or switched over rather into full ketosis,

Andrew Huberman 1:07:32 and ketogenic diets done properly can be great for people. The problem is if you do it wrong, you can really mess it up.

Lex Fridman 1:07:38 Yeah.

Andrew Huberman 1:07:38 I tried it once and I basically got psoriasis. I thought my scalp was gonna fall off. I was like sloughing off all this... It... And then I stopped and I was taking the liquid ketones...

Lex Fridman 1:07:46 Mm-hmm.

Andrew Huberman 1:07:47 ... and then all of a sudden I felt better again. But I was told that I just did it wrong.

Lex Fridman 1:07:52 Yes.

Andrew Huberman 1:07:52 Um...

Lex Fridman 1:07:53 That's right, it's-

Andrew Huberman 1:07:53 So I think there's a right way and a wrong way and you have to get it right.

Lex Fridman 1:07:56 Definitely. And so I've experimented quite a bit with keto to, to see how my body feels and doing it the right way and following all the instructions, and there's definitely a huge difference.

Andrew Huberman 1:08:06 ... that, uh... Like for example, one of the things I discovered, everyone always said this and, but I tried this, uh, recently over the past year, is I started drinking, when I don't feel great, if I'm fasting, uh, bone broth, uh, chicken bone broth. Oh, yeah. And for some reason, like magically, it could be, this is the other thing, the mind, I don't know, but it makes me feel really good. Oh, well, it could be the salt. It... So, I mean, neurons, the action potential of neurons as you know is sodiums rushing into the cell. You need enough extracellular sodium in order for your brain and nervous system to function. And so salt, I mean, unless people have hypertension, salt is great. There was an article in Science Magazine about a decade ago about how salt had been demonized and unless people have hypertension, provided you drink enough water, salt is great. You need sodium, magnesium and potassium to function. Mm-hmm. And for your nerve cells to work. I mean, people who over-drink water and don't consume enough electrolyte die. Mm-hmm. Um, now hydration is really important. I know David's really into hydration. He's mentioned that a few times. I mean, hydrating properly is key, and so you definitely want to make sure that you're drinking enough water and getting enough electrolytes. That, I'm, we should've actually talked about that at the beginning because that's gonna keep your nervous system functioning well. Yeah. And a lot of people, they'll get shaky or jittery, and, when they're fasting, and they'll think they need sugar. Yeah. And if they just put some salt in some water, they feel fine. They want it. And like the other stuff, uh, potassium, magnesium, whatever the other electrolytes are, but yeah, the... Yeah. Yeah, those three. So I mean, salt, yeah. Salt is a primary one. Magnesium is good before sleep. Um, salt. The, I mean, this is a vast space and we're kind of talking about the overlap between neurochemicals, hormones, and nutrition, and it's a fascinating space and it's one that the academic community has gems up within the textbooks. It hasn't really made it into the public sphere yet, and I think that's because people get so caught up in the, you know, being, are you vegan or are you carnivore? And there's a vast space in between too, that people can explore. Like, I'm not a competitive athlete, so I eat meat and I also eat vegetables and I eat fruits and it's just about timing them. But I tend to eat carbohydrates when I want to be sleepy. I eat them at night. And everyone said, "That's the worst thing. You can't do that." You sleep great after eating a big bowl of pasta, I'll tell

Andrew Huberman 1:10:22 you. (laughs) And by the way, I sh- I should, uh, give you a big thank you for connecting me with, uh, Belcampo Farms. Uh, they sent me some meat, I think because of you. (laughs) And it's delicious. So I, I, I really... Good. ... I really, uh, appreciate that. I mean, it also connected me with this whole world of people who are doing farming in this ethical way and like really love the whole process, and like, and as, uh, from a both like a human level but also scientific level and the result is, um, it's like ethical, but also it's delicious, and it makes you think about your diet in a whole new kind of way. Yeah, I've known, um... I don't have any commercial relationship to Belcampo, so I can be very clear. I've known Anya Fernald who, who's the f- one of the fou- is the founder and CEO of Belcampo, I've known her since the ninth grade. It, it is true that her parents are faculty members at Stanford, they're colleagues of mine. But she's just a serious academic of nutrition, but also of sustainable agriculture, of, you know, all sorts of things. And also the meat just... It's awesome, it tastes really good. And no, I'm not getting paid to say that, and no, they're not sponsoring my podcast, it's just if you... I feel like if you're gonna eat animals, if that's I- in your framework and you're gonna eat animals, knowing that the animals were raised a- as happy as could be until, you know, time of slaughter is, is imp- at least important to me. And, and I actually, uh, talked to her. So I, I will talk to her on this podcast actually, and she invited me, uh, like a week ago out to, to visit the farm in May or June or whatever. Oh yeah, they have the farm up at the Oregon border. Yeah. I haven't been there yet but I've seen the pictures and it's just beautiful. It looks awesome and I was like, "Yes." (laughs) Yeah, yeah. Looks beautiful. Let me know when you're going. Yeah, let's go together. Yeah. Yeah. I mean this is, it's... You'll probably run there but I'll drive there. (laughs) Yeah, but that, all that said, I do want to, 'cause I, a lot of people who are vegan write to me, and I do want to seriously, in the same seriousness that I approached keto, I do want to go like on a few months to, to switch to a vegan diet at some point to really try it. Yeah. I haven't done it yet 'cause I'm afraid I'm gonna function better. (laughs) My... I'm Argentine by my dad's side and I, I... Yeah. I don't eat, I don't eat meat super often but, well, for most people it would, it would seem often but, um, but I, I do love steak. I do. Um, so I'm afraid I'm gonna feel better. There's a social element to steak, you're right, 'cause coming from a Russian background like I can't imagine going to visit my folks, uh, like my parents for Thanksgiving or something and say, "Mom and Dad, I'm, uh, you know, ah, I don't eat meat." So instead of, you know... Well, I think if you're gonna eat meat- It's- ... getting it from sources that are compatible with, um, a, you know, continuation of the planet is good. I mean, there are some p- some real problems with the factory farm meat. You know, you drive up and down the 5 and you pass that point where there are all those cows. I mean, as somebody who loves animals, um, it's, it's clear that it's, you know, you want to limit the amount of suffering of those animals. Whenever I hear about, um, you know, we have, we know people that hunt and that go and get their own meat, I, I really admire that. I admire that people do that. Yeah. Uh, we don't, we don't tend to do that in the hills around Stanford, you know? (laughs) The- there're mountain lions back there but that's about it. And I'm, I'm certainly... I, I admire the vegan mindset of being, of just making that decision, you're just not gonna consume other beings but, you know, I haven't gone that way. But performance wise, I'm just curious because I was surprised, I was certain that eating five, six, seven meals a day is the right thing to do for all, if you want to be... Perform your best when I was like 20 or whatever. And I would eat oatmeal, like I thought it's obvious I have to have a really... A lot of carbs in the breakfast. I, I had a lot of preconceived notions and then when I started eating like once a day, this was at the peak of my competing in jujitsu, uh...

Lex Fridman 1:14:15 It, it was like everything I know about nutrition is wrong.

Andrew Huberman 1:14:19 Yeah.

Lex Fridman 1:14:20 You realize that like you have to become a scientist... First of all, you have to read literature, you have to learn, you have to experiment, but you also have to become a scientist of your own body in, in the same way, I have a lot of preconceived notions of what performance is like under vegan diet, and I want to do it right. S- like, seriously, not, not necessarily for the ethical reasons, but to see if it's performance-wise, like, can I... (laughs) I remember there's like a fruitarian diet where you eat fruit only. You know-

Andrew Huberman 1:14:50 These extremes are like... They're pretty, they're interesting 'cause people have this need... The extremes are informative though, right?

Lex Fridman 1:14:57 Right.

Andrew Huberman 1:14:57 I mean, well-controlled experiments, you eliminate as many variables as you can except the one you're interested in.

Lex Fridman 1:15:02 Mm-hmm.

Andrew Huberman 1:15:02 So, people are running these experiments. I, I think that the... It's hard to imagine getting... I know people say you can get enough amino acids from plant based sources, and I believe that, I think it probably takes a little more work. Um, it... One thing that's really clear is the, the benefit of these, um, omega-3, omega-6 ratios, like fish oils and things like that. There are some data that show that the getting at least 1,000 milligrams of the EPA, which is in... high in fish oils, but other things too, even some meats and other plants, it... In double, uh, you know, in matched, uh, placebo, double blind controlled studies, placebo controlled double blind studies have shown that those can offset antidepressive symptoms as much as some of the s- selective serotonin reuptake inhibitors like Prozac and Zoloft, so that's pretty impressive. And in Scandinavia, people know, especially in winter t- to consume a lot of those omega-3s because they're good for you, they're good for the brain.

Lex Fridman 1:16:03 That's the other question, um, nutrition wise, w- what kind of stuff have you come across that's useful? Like, I basically only take fish oil, like you said, electrolytes, just electrolytes with water, the David Goggins...

Andrew Huberman 1:16:17 Mm-hmm.

Lex Fridman 1:16:17 ... diet.

Andrew Huberman 1:16:18 Fish oil.

Lex Fridman 1:16:18 Plus fish oil, and then, uh, again, the sponsor, I... They've made this so easier, the, the sponsor of your podcast and, and mine, athleticgreens.com/huberman.

Andrew Huberman 1:16:28 It's great stuff, yeah.

Lex Fridman 1:16:29 Go support it. I don't, I don't know, like, it's, it's great stuff for sure, but also just takes away the headache of like, I don't have to think about, like...

Andrew Huberman 1:16:37 Yeah, you're gonna get a bunch of vitamins and minerals, you know, co-... does that... It sounds like a, a plug, but I have genuinely been buying it on my-

Lex Fridman 1:16:45 Yeah, yeah.

Andrew Huberman 1:16:45 ... you know, no discount, no affiliation or anything since 2012. I think I heard about it on the Tim Ferriss podcast, I was like, "Oh, I'm gonna try that stuff," and I liked it. I mean, when I was starting my lab, I was working insane hours. I still work very long hours, and getting sick limits productivity, and I also wanted to train and I wasn't doing much training back then. Um, now I try and get, you know, three, four sessions in a week. I'm not doing nothing like what you and David are doing, or what, you know, Joe does, or like... You guys are way more regimented and consistent than I am. Um, but I think that being healthy and feeling good is one of the great benefits to a career, is having energy and just being not sick.

Lex Fridman 1:17:28 Can we take a step back to, uh, uh, sleep for a little bit?

Andrew Huberman 1:17:31 Sure, yeah.

Lex Fridman 1:17:32 (laughs) And so people should definitely, uh, look through your podcast, the first five episodes were on sleep.

Andrew Huberman 1:17:40 Yeah.

Lex Fridman 1:17:40 Or m- no, I guess the first opening episode was, uh...

Andrew Huberman 1:17:44 First one was sort of how the brain works generally, it was to give people some background, and then we did four episodes on sleep.

Lex Fridman 1:17:49 Uh, yeah.

Andrew Huberman 1:17:50 Including some stuff about food, temperature, exercise, jet lag, shift work for the jet lag folks and shift workers.

Lex Fridman 1:17:56 Yeah, it's like a master class on sleep, and then you're go... You're going on to a next, uh, topic in the next few episodes, which is, uh, incredible. Well, neuroplasticity, we'll, we'll talk about it, but on sleep, one of the cool things about the human mind when it sleeps is dreaming.

Andrew Huberman 1:18:13 Mm-hmm.

Lex Fridman 1:18:14 Uh, wh- what do you think we understand about the contents of dreams? Like, what do dreams mean? All the stuff we see when we dream, is there something that we understand about, uh, the contents of dreams?

Andrew Huberman 1:18:32 Some of it is very concrete. So, um, Matt Wilson, who... MIT, yeah, um, showed in rodents and it's been shown in