WHOOP Podcast - Circadian health: Dr. Samer Hattar explains how light exposure affects your sleep, digestion, and exercise

Episode Date: June 29, 2022

On this week’s episode we take an in-depth look at the science behind your circadian rhythm and how light exposure affects your body. WHOOP VP of Performance Kristen Holmes sits down with Dr. Samer Hattar, a world-renowned expert in the field of circadian health, who is credited with discovering neurons in the eye that set our circadian clocks and regulate mood and appetite. Dr. Hattar explains the light-dark cycle and the circadian clock (3:44), the consequences of viewing light at the wrong time (6:34), the importance of light exposure in the morning (12:44), viewing light during the day and blue-light blockers (15:35), what happens when we are exposed to light at night (16:55), circadian health and digestion (19:37), eating windows and meal timing (25:07), exercise routines (28:46), new WHOOP Journal additions on circadian health (34:25), time zones and shifting your circadian rhythm (36:37), and your body's temperature minimum (40:15).Support the showFollow WHOOP: www.whoop.com Trial WHOOP for Free Instagram TikTok YouTube X Facebook LinkedIn Follow Will Ahmed: Instagram X LinkedIn Follow Kristen Holmes: Instagram LinkedIn Follow Emily Capodilupo: LinkedIn

Welcome back to the WOOP podcast, where we sit down with top athletes, researchers, scientists, and thought leaders to learn what the best in the world are doing to perform at their peak and what you can do to unlock your own best performance. I'm Kristen Holmes, VP of Performance at Woop, and we are on a mission to unlock human performance. On this week's episode, we're going deep on your circadian rhythm and how light exposure affects your body. I sit down with Dr. Sammer Hattar, a world-renowned expert in the field of non-image-forming photoreception, or how light affects circadian rhythms, sleep, mood, learning, stress, and hormone levels. Light has an enormous impact on performance levels. Dr. Hattar is credited with discovering neurons in the eye that set our circadian clocks and regulate mood and appetite, which was a groundbreaking discovery in the field of circadian health.

Dr. Hattar and I discuss what the consequences are. are if you view light at the wrong time, the importance of light exposure in the morning, how light exposure can affect our next day, mood, and behavior, synchronizing eating windows and meal timing with our internal clocks, and how disruption of the circadian rhythm has significant influences on exercise function. Knowing how important circadian alignment is to your overall health, we've added the ability to track circadian health questions in the Whoop Journal. Check them out in the Whoop app and get tracking today. We also have an exciting new offer for WOOP podcast listeners. If you're a new member signing up for

WOOP, use the code will, all caps, WI-L-L, when you're checking out to get a $60 credit on WOOP accessories. That includes bands, battery packs, and our WOOP body apparel. Head to join.Woop.com to get started. And now here's our discussion with Dr. Samra Hattar. So honored to welcome chronobiologist and the chief of the section on light and circadian rhythms at the National Institute of Health, Dr. Samra Hattar. Dr. Hedar is a world-renowned expert on how light affects circadian rhythms, and his discoveries have helped us to better understand how the relationship between light viewing, exercise, meal timing, impact our sleep, mood, energy levels, learning,

stress and hormone levels, hunger, satiety, as well as our mental health. I think the best analogy for human health is that of like building a house. If your foundation that's been poured is misaligned or is not optimal, you're gonna have leaks, you're gonna have mold, your house is just not gonna be as stable as it could be.

And I think that's a great way to think about our human health and really Dr. Hattar, where I want to like focus our energy is around this concept of foundation. What are the behaviors that really impact our ability to have this really solid foundation that enables us to stack on other behaviors in a way that's as efficient as humanly possible? Because I always think if that foundation isn't right, it's just layering inefficiency on top of inefficiency on top of inefficiency. So when we talk about, you know, where do we actually have to,

apply our effort at a foundational level, I'd really love for you to help us think about that. You have developed this incredibly elegant way of thinking about a model for optimal human functioning, and perhaps we can kind of start there, and really with, perhaps with light. So I will start a little bit earlier, if you don't mind. Oh, please, yeah. All organisms that ever lived on earth, at least even simpler organism like cyanobacteria, have experienced the light, dark cycle. So the earth have been taking information for billions of years, and you have this rising of the sun and setting of the sun. And so most organisms that we studied really carefully have a circadian rhythm.

Circadian means circca means approximate and DNA's day, so it's an approximate day within. So this is your foundation. foundation is that your circadian clock has to be aligned with the light, dark cycle that give all organisms the time of day. For plants, it's easy to do it because they are sitting there, enjoying the sun, and getting the information. But for us, we as a human, specifically after all these years of evolution and the importance of this clock, and we forgot that we actually have a clock that is not a watch. And so we really abused our clock a lot. And we started thinking we don't need sleep or if you sleep long time you're stupid or we came up with

all these dumb ideas and what we forgot is that that is affecting our foundation and that is affecting our energy level that is affecting our cognitive ability so yes we could overcome it but if we had the foundation better we could do even better so thinking about that i came up with the model that you mentioned i figured out that there is at least three components that's seems to affect every behavior, an environmental input, mostly light in our situation, could be food, could be temperature, and we'll talk about all of that, a homostat that measures the length of time that you're doing something, and the clock that tells you the time of day. And it is these interaction with these three components that will allow you to understand

behaviors at a foundational level that becomes very important for his. humans to try to adjust. So essentially, removing ourselves from the natural environment in this modern world has basically confused our clock potentially. Not only we removed ourselves. I mean, we did something even more dumb. We not only removed ourselves, we stopped going out. We started actually exposing ourselves to very bright lights at time when our body should not be exposed to bright lights. So not only we removed ourselves from the day-night cycle, which could have been bad, but we also told our buddy at home that, you know, this is the day when it's in the middle of the night. So we actually literally flipped our day when our activity is still, you know,

diurnal, we flipped our day to be nocturnal. So what is the consequence of viewing light at the wrong time? Because really that's what you're saying, right? We're viewing light at a phase of the natural light dark cycle. Yeah. Yeah. I mean, the consequences has been studied, you know, adnosium as they say, and it affects your sleep. When you have sleep deprivation, it affects every physiological function in your body. Sleep has incredible restorative functions. It has an amazing importance for your ability to learn and memorize.

In fact, studies have been done that are beautiful, showing that if you study something, sleep on it, you learn it much more than if you study it and you don't sleep on it. So, in fact, when people pull an all nighter, not only they are destroying themselves, but they are not actually allowing the consolidation of the material they learned. So it's double disastrous. You're affecting your clock and you're not allowing sleep to come in and do stuff.

And then when you start eating at the wrong time of the day, there's a huge amount of research that's just showing that eating at the right time of the day by itself has a huge advantage to your body in addition to calorie restriction and in addition to fasting, but specifically eating just at the right time of the day has an incredible importance for your physiology. I want to definitely come back to that because, you know, Sachin Panda's work around just time-restricted feeding,

I think is really important. And I think that's another component. I think that folks don't consider when we talk about wanting to optimize our sleep and, you know, get the most consolidated sleep so we can learn better. Yeah. I would just like to add that there is a new paper from Vick's, Victoria Acosta from Jota Kahash's lab, that you combine time-restricted feeding, fasting, and calorie restriction. Wow.

And it's mind-boggling. It's in science. I've read this paper. I talked to Victoria. It is just an amazing study that shows that all three components play a role, not only time restricted feeding, but calorie restriction and fasting all are important. These are, but if you think about it again in the model, it will make sense, right? You're not supposed to be eating 24 hours a day, so fasting is important. You have to eat at a certain time of the day, so time-restricted feeding is important.

And too much calorie actually will have negative consequences because you're adding all these components to your body which you don't need. But thinking about that in the context of light is really, is critical. It has to be. It has to be. So I think just to go back to sleep, again, I just want to make sure that this is really clear because I don't know that people realize, you know, when we talk about office, optimizing sleep, you know, getting more consolidated sleep, more efficient sleep, people think

about their pre-sleep behaviors. They're going to think about, and maybe their hygiene, which are important. I'm sorry, do you mind if I interrupt you one second here? That's the problem. This is important. Sleep hygiene is important, but that's one component. And sleep hygiene is going to mostly affect your homeostatic drive. Right.

But if your clock is out of whack. Which is your pressure for sleep. Which is your pressure for sleep. But if your clock is out of whack, sleep hygiene is not going to help you. Exactly. Yes. So what you need to think about is the three component. Homeostat, circadian clock, and environmental input.

Your circadian clock is not going to be as efficient and it's beautifully robust if it doesn't get light-dark cycle. Right. So you need the light-dark cycle to be good. You need your morning sun. You need enough sunlight. You need enough light intensity in the day in your active phase. And you need to avoid dark, you know, very bright light in the dark. And you don't have to think of it as wavelength, just think of it of intensity.

It's very easy to lower the intensity and do the experiment that I always talk about. Every time go to your house, cut some lights out, allow yourself five minutes to adjust, and you'll be shocked how much more light you were using in your home than what you need it. It's a very simple experiment. People are good at perceiving light intensity. You're absolutely right. Right? It's actually very sad.

It's so sad. It's sad, but it's also evolutionary understandable, right? I mean, to be able to see you, I have to look at contrast. I don't care about that. Otherwise, I will see you a different person in the sun and in the shade. To be able to see you as Kristen outside and inside, I have to look at contrast, edges. And in fact, people even now think that color vision is really a contrast. It's not really color vision.

It's a contrast. So if you think about that, it makes sense that you don't care as a visual cortex, as an image-forming system, to actually see the total intensity of light. So consciously, a conscious part of your brain cares about image, object tracking, if something's coming to eat you or if you're trying to eat something, but the total intensity is all subconscious.

So you have no idea what is the intensity. You have an idea, but not a lot. Believe me, not as much people as they think. Yeah, that's incredible. It is. So to go back to just the protocols around viewing light, You know, one of the things that I see in the research that we're doing around mental and physical resilience is we're trying to really tap into what are the behaviors that move that around.

So move around the physiology, move around the psychology. And what we've found is that sleep wake time continues to emerge and be predictive of mental and physical resilience. And my hypothesis is the folks who are able to achieve consistent sleep wake times are obviously making a very intentional choice. but I think it also probably has something to do when they're viewing light in the morning. Absolutely. So if we want to help our listeners, you know, since we know, sleep wait time is really important. People are striving to be more consistent when they go to bed, when they wake up. How do they need to think about viewing light in the morning?

Basically, that pulse of light is then going to set course for how one builds that pressure for sleep, right? Right. I would suggest a couple of things. Once you don't have to be worried about like exact timing. It doesn't have to be with the, you know, rising of the sleep. sun. You also have to think about where you are in your biological rhythm and where you are in the phase relation to the light dark cycle. But in general, when you wake up from bed, you take some time, you get up, and if you can go outside and, you know, if the sun is up already, take that

sun. It doesn't hurt you. And you don't have to stand in the sun directly, so you don't want to worry about your skin or you could be in the shade. Outside, in the shade, in the sunny day, you're going to get tons of photons that are more than sufficient. And that's telling your body what? That is literally, actually, if you want me to go a little bit deep here, the photoreceptors that we help discover are really very insensitive to light. In a way, they need a lot of light before they start signal to the brain, which is nice evolutionary so they don't confuse low light with bright light. So when these cells are activated, they actually directly project into your brain and to areas that we know control, sleep, circadian rhythm, and mood. So we actually know the circuits right now. Some of it's still in rodents, but most of it in humans as well, that light can really

enhance the activity and function of these brain regions. So honestly, I always tell my friends that getting light in the morning, like getting a drug that has nearly no side effects if you don't sit in the sun and hurt your retina or your skin. And it really is free. Like it doesn't cost you any money. Right. And it's just fantastic. The impact is outsized compared to, you know.

Honestly, and again, I think there is a lot of data that convinced me, but I'm also biased because I see it in my whole life. Yeah. I think the impact is amazing. And I had sleep doctors who told me that once I heard about your research, and I just told my patient, do some sleep, sorry, light hygiene, just simple light hygiene. Yeah. Switch your lights off, you know, go out, take some sun, you know.

they said they will come and say, change my life. I mean, is that scientifically correct? I don't know, but I've heard this over and over again. I've read it over and over again in the Internet when people say, I've changed this, and this is what happened to my life. So it seems like it's a no-brainer to do it and see how it affects you.

I heard you say once, take a photon, not a pill. And I love that because it's such a simple way of communicating the importance. for it because they think that I don't like pills. The pills have their role and I'm fully vaccinated and I believe in medicine. Right. But I'm in the point is don't just go to the pills first. Take your photo and try something and then, you know, if that's the only way, yes, I take

pills, you know, it's okay. And I think if we go back to the house analogy about layering an efficiency on upon efficiency, how do you rule out medication if you have, if you're not taking in morning life? Absolutely. Right. Exactly. I mean.

You may not need as many medication. Exactly. Always talk to your doctor about medication. that's beside the point. So viewing light in the morning is important. How do we need to think about viewing light during the day? We've got obviously lots of blue light blocking glasses. People are trying to block waves of light all over the place.

Blocking blue light in the day, that is just dumb. I'm sorry. I'm just not going to be like. No, tell us straight, Sammer. This is why we have you on. It just doesn't make sense. We want to know. Blocking it at night may make some sense, to be honest.

But again, I still think there are ways to do it without having to do different. in contrast and affecting your vision because that is going to also like we don't see pure colors in nature. I mean, it's really hard to imagine to see the world in a single color. So I think for our vision, because again, I think as a holistic approach, we were talking about the tri-party. You could also imagine light affecting your clock, but giving you a good mood by the beauty, like when you're in a beach or a beautiful forest or you have people who look nicer, you feel better, right? Yeah, the spectrum being, having the whole spectrum spectrum of light so i i'm not so i may be biased but it's not my cup of tea i have to say after the sun

goes down i am viewing as little light as humanly possible um you know i i don't know how effective the filters are you know there are times the filters they decrease the intensity they are right right they're pretty effective so i think but the bottom line is if we're viewing light after the sun goes down it's going to have an impact on our system you're exposing yourself to light at night, you're possibly affecting the other important physiological function that light controls. Do you think it's impacting next day mood and next day energy levels? I would say that it depends on the behavior. For mood, it requires more time, but it also required more time to adjust. So the problem I think is that, again, it's a beautiful time domain. Some stuff happens

fast, some stuff requires a long time, but there are people who become so unentrained and so unaware of the light that they become so misaligned that their body doesn't feel the pain consciously, but their system is out of whack. If you measure their system, you could see that it's all after whack. So I think that's what eventually leads to, so the reason I don't want to say the next day, because I don't want people to get scared that if I went out partying one night, I'm screwed. No, you're not. It's accumulated. You're going to feel a couple of days unhappy, but if you get back to it, you'll be fine.

But don't do this all the time. Don't have this as a habit. Have the habit as the light hygiene aspect of it. So if people wake up, have low energy during the day, low mood, the question that they should be asking themselves, potentially, the very first question is, when and how am I viewing light? Honestly, I've never thought about it this way, but I love this idea. It's the simplest thing they could do. It doesn't require any extrajust, let me see. It's no expenses.

Yeah. Most probably maybe, you know, a lot of the people may not be because of that. But hey, let me try it. Let me see what happens if I have a light hygiene. I did a search on just looking into, you know, how does mental health affect my physical health and vice versa? And, you know, what are the recommendations psychologists are giving, to be clear, that is my field of expertise in psychology, but I spend a lot more time thinking about

physiology but I found nothing about light hygiene nothing there is nothing people say there are some recommendations get out in nature but it's not specific sammer and I think people need kind of specific recommendations on how to think about life I honestly think that just if you're feeling low if you're having problem sleeping just thinking about your light environment and try to improve it costs you nothing it's just going to lead to improvements right so I think that's a brilliant idea I'm all on it. Okay, let's talk about the relationship between light and food and sleep. Yes.

So walk us through kind of what that interaction looks like and hopefully how folks can think about the phase relation. The enzymes that are secreted to digest your food have a daily rhythm. Right. And they are the liver enzymes, the bile enzymes, the spleen, the kidney, all of them have a clock that have a phase relation. Just again, like the symphony idea. Yeah.

And when you're in train, exactly, when you're in train, you're eating your foods at the right time of the day, you're having a regular feeding pattern, everything is perfect. And that's the time restricted feeding. It's not that complicated of an idea. So a lot of people will fast until, so I generally eat around 11 for my first meal. So I'm kind of restricting my window to about eight hours. So I'm eating food within an eight hour block and then not eating the rest of. of the time now not everyone needs to do that so maybe just the more light eye view in the morning actually the less hungry i feel is there is there anything to that or not not that i know directly

where food can affect appetite or hunger but what it's possibly happening with you because you have again adjusted your oscillators to expect food at a certain time because remember i'm anticipating you're anticipating it's like again this paper by victoria blew me away it's Really, this experiment, I looked at it. What is her last name again? Victoria Acosta, I will email you her name. But one thing that really blew me away, she did a very cool experiment to tell the difference between fasting, calorie restriction, and time of day, where she gave the animals a pellet

every two hours. Okay. And believe it or not, so every two hours and a 24-hour day, that means the animal have to anticipate it 12 times in a day. That seems really expensive, costly. expensive but second can they do it they do it beautifully that's how powerful the clock is that's how powerful it has a 12 component i will show you the octograms you'll be stunned like i was stunned what it it's unbelievable it it's like so it's not only like if you restrict their food to seven

hour or six hours a day they'll anticipate that food they literally can't anticipate it in multiple times in a day so you can train yourself exactly exactly I mean, and that's the opportunity, right, I suppose. So what you've done because you have the will, you said, okay, I'm going to wake up, expose myself to light, have my oscillators in a certain time. But the food intrainable oscillator in the periphery, and maybe there's one in the brain, we're still not 100. But at least the one in the periphery is going to expect your food at 11 a.m. So you're not going to get hungry before that. Right.

Okay. So with time, again, this is going to give you more control. So that's what people forget. like people think it's all subconscious, but actually it also gives you conscious control. Right. Because now if you're exercising at the third time of the day, if you're eating at the same time, if you're sleeping,

now this becomes natural. And people are like, why is she show much energy? Why is she able to go to the gym all the time? Because you have all these components alike. And it goes back to a simple point you mentioned. It's all foundational. Right, right. Okay, so regularity is critical.

Absolutely. Absolutely. We can't be eating for 12 to 15 hours, right? That's not good for our system. So I suppose we wake up and we have breakfast. Let's say we have three regular meals. What should the interval of time be? I always say for simplicity, I just eat when the sun's out.

And then I try not to eat when the sun's down. I could tell you with me, it's really funny. Like I am a morning person. I wake up really early in the morning. By 7 o'clock I'm eating. By 2 o'clock, I'm still hungry and I have to eat. Like, if you don't give me any food from 2.30 till the next day, I will have no problem. I only eat for social because I love to eat.

But I don't feel the hunger. So my clock tells me I have to eat from 7 to 3 or something like that. You just have to figure out your clock. And as you said, if you don't feel hungry in the morning, don't believe people will tell you you have to have breakfast. If you don't feel hungry, don't eat. And, you know, just eat the time that your buddy's telling you eat. And then with more regularity, you will figure out what is your body's phase relation between all these different oscillator and what is the best time to eat, what component. So what would be, you know, it's going to vary, you know, per individual, for sure.

We're saying there's lots of variation between my clock and your clock. So there's a lot of variation on the output, but there is not a lot of variation on the input. And so I just want to make sure that that's the beauty about the light. because the light in the morning is going to be as important for a morning person, an evening person, an animal that is olfactory, they are all going to tell the same story. It's the day. Now, when you want to do stuff, it's dependent, but the input has to tell you when is the exact day's happening, right? Right, right, totally.

Let's just talk a little bit about this window of time as such. And Panda's work says it's somewhere between 8 and 10 hours is really good. They did an experiment and they saw that people actually eat more like for 50, 15 hours across the day, which is... That experiment was shocking. It is mind-blowing, right? To really know that we eat, are we eating constantly? Yeah.

What implications does that have if we're eating for 15 hours? And, you know, what does the science tell us about restricting that window between 8 to 10? I mean, I could tell you something that we've knew of circadian biologists for so many years. When you eat, you're shifting your clock in your periphery. Yeah. And if your body is still thinking it's night and you're... your clock should be in the nighttime, the digestive clock, that by itself has already caused misalignment.

So just by eating at the wrong time of the day, you're causing a misalignment. It's not. You're confusing your system, making it work harder. Exactly. And so it's really just amazing. Like, again, in these experiments, you could show that you could give the same amount of calorie, the same amount of fasting, but given the right time versus the wrong time, and you get a huge difference.

I mean, that is just. That is just mind. Content and quality of food obviously matters, but timing is merging as just as important. And I love to talk to you, Kristen, because as a minimum of three, but you could add to that, right? You start eating better food. Right. Yeah. Your system's working more efficiently.

You start craving the right kind of foods. And I think this is the opportunity. And this is what I'm so excited about your model is that timing is free for the most part. There are folks, obviously, you have big constraints of when they need to go to bed and when they wake up, you know, shift working and that's all I've said about that I take my hat for these people and I respect that they keep us right but that's not an easy job and that's why not many people can do it that's brutal these are levers like if we understand how to interact with light when I'm working during the night and the day I have to say I still never figured it out for shift worker it's just so hard

you could lower it I know lower the intensity and lower the impact like you know make sure that at least if you're shift working, don't switch to a lot. Again, take regularity, very simple, make it as a longer time. But it's still, it's not going to be like you and me where we have the freedom and the privilege to sleep and wake up. So that's something that bothers me. Yeah, it's really hard.

In Denmark, now they consider shift work. A carcinogen. Yeah, because they notice in nurse. I mean, it's just, it's not that crazy, right? I mean, because the... No, we know, it makes a lot of sense. And I believe these conversations are important because I think the truth is really important. And I think it gives us, when we have the right information,

we can start to make these small changes that actually, over time, I think, do have a... I'm hopeful that they're going to have a meaningful impact on mitigating, you know, some of the diseases and... You know, I think one thing we could do, for example, is, like, I don't know if you're thinking about that, but I thought about this, if you want to help shift work or not to suffer so much, is to lower the amount of hours. You can't expect shift waters to work eight hours like us. You make like four hour shifts or five hour shifts. Lower the light intensity, make sure because they are short shifts

that they're not going to go to sleep in these lower light intensities, but then have somebody drive them home. So they don't drive when they are extremely tired or they have to be exposed to light or stuff like that. So I'm sure we could do stuff, and I'm sure you guys are thinking much beyond me because there are ways to do it. But we really have to be honest about the problem first, which is what you're saying.

Okay, so we've kind of tackled light. We've tackled, I think, feeding windows. Let's talk a little bit about exercise, because I think that's another one that really entrains our clocks, our system in a pretty powerful way. How can people think about when they are doing an intense movement, so not just, you know, normal activity, but they actually are working out? is there a timing to that? That's important. Is that also something that we want to try to make as regular as possible? Like, what are the parameters that exist?

I mean, if you look at animals, clearly there is a very clear window where they like to be active, right? So there is no doubt that the activity has a beautiful diurner rhythm. And there is no doubt that adding wheel or exercise for the animals give them more enrich environment. The problem is to try to separate the intense activity. activity, time of day of activity, and all on the effects. So what I really tell people is like, as long as the exercise is not so close to your bedtime that you can't sleep because you exercise, I can't see a negative aspect to exercise. Right.

Right. So whenever you can get it in, it's, you need to get it in. It just seems to be embedded into animals to be active. And I thought about this a lot, to be honest. I was like, and the reason I thought about it because I always struggled with weight when I stopped playing soccer and I was like, why is life so unfair that you need to work so hard

to burn like even half a snickers? Right. Right? Totally. And you think about it and it's a brilliant evolutionary reason. Because imagine if exercise was really efficient as burning your energy,

then you have to hunt 10 times more. Yeah. Then you will die hunting because your food is going to be depleted. A thousand percent. So you think about it. It's actually very simple. You don't want your exercise to be so efficient at burning.

So if you have to hunt or if you have to exercise. It just stinks in this world of abundance where we have to try to exert so much self-control. Exactly, exactly. So I think there is something really amazing about exercise, which I really cannot think what it is. It makes me think about how people thought about sleep in the past before we knew about learning and memory. and that it does something and you know they all measure all these positive outcomes right mood enhancement telomeres whatever

your looks feel energy but I still don't know why do you have to like why exerting yourself is important and one really impressive experiment that I think people don't know much about where if you knock out the clock only in muscle you actually affect sleep in the whole animal so somehow it's

seems that the muscle themselves, and if you think about how much muscles we have, maybe the muscles themselves are playing a role in enhancing our sleep, our, so having them in optimal conditions and being active. I mean, another very interesting observation, your grip strength is actually, you know that. It's one of the most important component of how healthy you are. A hundred percent, yeah. The Canadians have done a bunch of, Yeah, they're all over the grip research. Yeah. So we're starting to get some clues about why exercise may be important.

Because, like, you know, maybe if your muscle degenerate, now you're not taking as much sugar for your muscles, so sugar is floating around. I don't know. Insulin goes up. Insulin going up is not important. But if you have more active muscles, they absorb glucose and the clock there is more. So this is all speculation and based on my reading. Right. But it's something I would love to go.

into, but I'm just so into the brain right now that I haven't done a lot on that. Wow. Yeah, that'd be really interesting to understand. But I have to say there is no doubt if you look at most experiments, most of that, that the lack of activity, not necessarily intense activity, but just the lack of activity has an incredible correlation, and we know correlations are not causation, with unhealthiness. Right. There is just simply no doubt about that.

Yeah. There is something about activity. You know, I think we see in our data that when folks are below their typical activity levels, they don't get into deeper stages of sleep. And of one anecdotally in my own data, there's no question that when I am just at my computer, like, grinding away, you know, and not able to kind of do my normal activity of level, just even walking around, you know, just the non-exercise, you know, kind of activity. Now, the evidence that exercise increases homeostatic drive, isn't that, I should check that.

Isn't that proven? For sure, yeah, there's no question that exercise is going to increase, you're going to want to fall asleep sooner, for sure. And it's going to improve the level of deepness of it. Yeah, yeah. And we always, you know, what we do at WOOP, we have an algorithm, it's kind of our sleep need recommendation. Oh, I see. And we basically tell you how much time you need to spend in bed. And one of the factors, one of the variables that we use to inform that algorithm is how much

activity you've done. So what your cardio, and not steps, cardiovascular load, right? Because there is, there's load. I think that is going to, it's not just physical load, but it's cognitive load as well, and that manifests in your heart. So that is, there's no question that I think the amount of load you put cognitive physical, and we call the strain on our system, is going to inform how much time you need to spend in bed in order to optimally regenerate for tomorrow.

So I think no question that the less activity you put in your body, generally speaking, the less time you need to spend in bed. But what's interesting is not the reduction in how much time you need to spend in bed, but it's actually the reduction in the quality of sleep that's interesting to me. That's the problem. That's the problem. And when we are not active, we simply don't sleep as well. We sleep lighter.

We don't have the drive, yeah. So anyway, I think that there's a lot to do, I think, in that space for sure. We launched a new feature in the app, which we're really excited about. but it gives people the opportunity to think about their circadian health, and they're going to have the opportunity to really start to think about the relationship between their light viewing and meal time. Wonderful. And that would be great.

I would love to see this day. I know, I know. And that's what's really cool. So I've kind of put this laundry list of questions that people will be able to journal about and with some really specific parameters in terms of magnitude and frequency and whatnot. So what will be great is we'll end up with this. really neat data set hopefully that we can start to kind of knit together and then it may prove like the importance of like the input being consistent but you could be much more flexible and plastic

with how you align your other outputs yes definitely and how they might impact each other you know because if i'm doing one then all of a sudden my behavior around absolutely feeling might change and i might feel more energy to exercise at a certain time if i start viewing light more consistently and really dimming, you know, my evening light viewing. And yeah, so we're really excited about that. That's really cool. And, yeah, so this conversation is going to help, you know, hopefully just launch this to our members to really start to think about the relationship.

But I would love to really figure out how we can kind of measure light. So people can just get a framework for because, as we said in the beginning, you know, we're really bad at perceiving light. I honestly think that's the, that's the holy gray right now, is to figure out how we can get sensors that are close to our eyes because putting a sensor here and I'm looking there it doesn't mean anything right now right so you really have to have a sensor like I sometimes hope like we could put something like that just like a little chip right there yeah that measure because that that I think is going to tell us so much more than we think but that's the holy grail right now yeah

I wanted to talk just maybe end on shifting the clock oh yeah we did this really cool experiment. So in my role at Woop, you know, do a lot of research. I do a lot of public education. And I used to work a lot with teams. And one of the teams that we worked with, a really high-performing collegiate soccer team, national championship level, they've got many internationals, Olympic level athletes and their team. It was incredible. So they were traveling from the East Coast to the West Coast for their playoff games. So I kept them on their East Coast time zone. So we kept their meals, light, and training time. When they went to the West Coast? On East Coast. So kept it regular. And what we saw

Samaran the data, no physiological changes. So their HRV stayed, you know, relative normal to their baseline. We kept everything. We kept everyone the same. Yeah. So it just reinforced this idea that, wow, if we stay in our home time zone. And we, you know, view light, of course, we were having, they were waking up at three in the morning. Yeah. So they're at, you know, they're at Stanford. And, you know, there's Santa Clara the other time. But, you know, they're at the. in this Pacific time zone, but, you know, we just, they bathe themselves in an artificial light, you know, to kind of wake up the system. And then they went down to have breakfast at 4 o'clock in the morning and literally kept themselves on East Coast. Yeah. So it was an

amazing experiment. And we replicated it. Honestly, I would have told you 100% that it would be but, but to get folks to do that though. Oh yeah, that's the hard one. That's what I was going to tell you. Getting humans to do things. My hands off for you. Exactly. Well, it's these women, they are just the tip of the spear. And they want to. to win a national championship and they did and they had the drive but it begs the question that wow okay we can actually acclimatize potentially by you know using these levers if we are traveling right or if i have a wedding in my own time so a lot of high end clients they do this they have done this that's why i would have told you it would have worked yeah if they can't travel first class but that's right

you know so they travel first class they sleep at their amount they go to that they They manage all their meeting to be within their day. So they have a very short period of time. They don't adjust to the new, but they don't see the city. They are in business. They come back. Nothing. It's like as if you went from Baltimore to Buenos Aires.

You know, the same zone, nothing happens. You know, last year, last October, I traveled from Boston to Salt Lake City, gave a presentation and then Salt Lake City to Milan. And I basically kept myself on my home time zone. No problem. No problem. And, you know, and it's amazing because I have all the data to be able to kind of show those no perturbations in my system. I would be shocked if there was any problem.

It's amazing. So I think that there's like a really cool opportunity for people to think about meal, you know, sleep wake timing, obviously, but think about light. Do you mind just to ask you what, how intense the light to use? That's what I would love to know. Not at least 900 lux of artificial light. So not that intense. Not that intense. So I wonder if this would work for a limited period.

of time because it may affect the clock but then eventually your mood is going to because mood is much less sensitive there's a lag there is a lag and remember i told you mood takes a long period of time so this is great for short period of time yeah but i would guarantee you it will not work for a long period of time that is so interesting okay so for short bounce of travel for short bout it's actually a brilliant idea if you're okay if you want to win all right if you want to win yeah and these are just this is literally seven days and what's great is these are student athletes so when they returned back home they were they had exams totally normal no problem so that makes total sense okay so short term yeah long term we'll have to deal with that yeah long term it's not going to be

feasible because right but you're gonna judge if you're staying somewhere for a long time anyway you're going to adjust to that time zone anyway and you're not looking for this kind of fix but it's brilliant idea okay let's talk about temperature minimum yeah because i think this is a really interesting it's an amazing lever as well that no one really recognizes so just temperature minimum is basically if you just average the last week of when you typically wake up naturally, your temperature minimum is two hours before that average time of waking. So if I typically wake up at 7 a.m., my temperature minimum, my lowest temperature of the day is going to be 5 a.m. I can't believe I didn't use that to explain my alignment. That's the whole beautiful thing

about alignment. Well, I wanted to make sure we hit on that. Yeah, yeah, you're right. Because this is really the alignment piece, you know, but I think practically. So what happens when you travel across different time zone is that your temperature minimum and your sleep are completely dissociated. Okay. So talk about that. Yeah, no, so you're right. So that's the beauty about the whole concept of the three components. The phase relation of your temperature rhythms, which is separate from your sleep rhythm, they are correlated again, but they are not really driving each other's most of the time, is that before you wake up in a certain hours, your body temperature for some reason goes to a very low level right and you know it it really decreases by sometimes up to one

and a half degrees right so and that relationship tells you a lot about how good your sleep is yeah because it's the synchrony between all your different orchestra players and so when you when your temperature minimum is happening when you're just going to sleep or when it's happening when you're active yeah that tells you a lot already that you're missing something right we need to get outside We need to get outside It's easy It's nice I know

It's free And you feel the seasons You feel the seasons In the cold wear a coat In the summer wear shorts Yeah exactly Who cares I love it

Well this has been such a fun discussion I could literally talk to you Me too Keep going forever But you've been so generous with your time And just your insights Have been just incredible I've learned so much

Where can folks find you Sam is it just your What's your handle on Twitter You're just Sammer Hattar? Yeah, I think it's my first. Samra with an E, Hattar with an A. Yeah, exactly. And then you're on Instagram as well.

Well, thank you so much. Thank you very much for the wonderful questions. Many thanks to Dr. Samer Hatar for joining us on the Woop podcast today. If you enjoyed this episode of the Woop podcast, be sure to leave a rating or review. It's a great way to share your feedback and to help other people find the WOOP podcast. Check us out on social at Woop. You can email the Woop podcast, podcast at Woop.com, or you can call our new listener line and leave a question or comment, and your question might be answered on a future episode.

Again, that number is 508-443-49-2. Thank you so much for listening to the Woot Podcast. Have a great week.