Dhru Purohit Show - The Science Behind When To Eat and Other Top Lessons On Circadian Biology

Episode Date: January 20, 2025

This episode is brought to you by Pique Life and Birch Living.  We used to think that the circadian rhythm only affected sleep. However, emerging science shows it’s deeply connected to metabolism, cognition, chronic disease risk, and many other critical aspects of health. Our biology is designed to function in harmony with the natural light-dark cycle, but modern society has significantly disrupted this balance. Today on The Dhru Purohit Show, we bring you a special compilation episode featuring Dhru's conversations with leading experts on the critical role circadian rhythms play in our health and well-being. Dr. Satchin Panda delves into his groundbreaking research on circadian biology, revealing how leveraging your circadian rhythm can significantly improve sleep, reduce the risk of chronic diseases, and enhance cognitive function. He also shares how time-restricted eating, exercise, and light exposure can help program your circadian rhythm, with a special focus on the importance of these tools for shift workers. Dr. Moore-Ede discusses the dangers of chronic blue light exposure and its profound impact on health, highlighting research that reveals how it disrupts circadian rhythms. He also examines the connection between light exposure and obesity and explains why these risks remain underrepresented in mainstream media. Dr. Satchin Panda, a professor at the Salk Institute and founder of the UC San Diego Center for Circadian Biology, is a leading researcher in circadian biology. Dr. Martin Moore-Ede, a former Harvard Medical School professor and expert in circadian rhythms, has conducted groundbreaking research on light's role in regulating sleep-wake cycles and overall health. In this episode, Dhru and his guests dive into: Why when we eat is more important than what we eat (01:38) Effects of chronic late-night eating (08:18) Adverse effect of disrupting our circadian rhythm (16:25) What is sleep debt (19:21) Paying attention to when you eat (30:16) Research on time-restricted eating (34:08) Why sleeping with the lights on is damaging to your health (39:01) Why sun exposure is critical for good health (41:55) Dr. Martin's recommended time for sun exposure (49:28) The link between blue light and obesity (51:42) Master clock of the circadian rhythm, cortisol, melatonin, and others (54:06) Why doctors aren't talking about the harmful effects of blue lights (59:03) Blue lights in hospitals and how they prevent healing (01:04:47) Also mentioned: Full episode with Dr. Satchin Panda Full episode with Dr. Martin Ede-Moore This episode is brought to you by Pique Life and Birch Living.  Right now, Pique Life is offering 20% off the Radiant Skin Duo plus a free beaker and frother when you go to piquelife.com/dhru. To get 25% off your Birch Living mattress plus two free eco-rest pillows, head over to birchliving.com/dhru today. Learn more about your ad choices. Visit megaphone.fm/adchoices

Hi everyone, Drew Brod here. You know, and most of us hear the term circadian rhythm, we tend to immediately think about sleep. But the truth is that our circadian rhythm reaches far beyond sleep with significant, significant implications for all sorts of things like your immune health, mental health, cognitive health, and your risk of all sorts of chronic diseases, including things like cancer. This is why it's so key to understand the role of our circadian rhythm

and how adopting lifestyle practices to support it and staying away from the ones that don't support it will have a massive impact on your overall health. In today's compilation episode, I'm talking with two experts on the topic of circadian rhythm. One of the first experts on the podcast is Dr. Suchin Panda. He's a professor at the Salk Institute of Biological Studies, a Pew Biomedical Scholar, and the founder of the UC San Diego Center for Circadian Biology. And he's also the recipient of the Julie Martin Mid-career Award in Aging Research. And in addition to Dr. Suchin Panda, we also have Dr. Martin Moore-E. He's a highly respected expert in circadian rhythms and the impact that light has on our health. As a former professor at Harvard Medical School, he's conducted extensive research on the role of

light in regulating our sleep wake cycles and our overall well-being and our risk of chronic disease. Okay, let's start off by jumping into my conversation with Dr. Such and Panda on the importance of circadian rhythms, as well as why we want the timing of eating, sleeping, and other daily activities to align with the body's natural cycles. I want to jump right in. Tell us about why when we eat, which is the timing of when we decide to eat, the window, might be just as important, if not more important than what we eat. Secadian rhythm essentially relates to almost a daily timetable of things that has to happen in our body,

whether it is fighting immune, fighting infection, metabolic balance, brain health, or even repair and rejuvenation for injuries. And when we think about circadian rhythm, then since it's a big new concept, it's also a little bit difficult to understand. but just imagine that in our life, daily life, we organize our life around time. We think of the whole day, what time I have to get up, what time I have to go to school or send kids to school, and then what time I go to work, what we do, and then in the evening, what time I have to meet friends or get back to home, what time we sleep. So similarly, every single cell in our body has its own 24 hours timetable. That means the cell has to decide, okay, this is the time I have to make energy.

This is the time when I have to recycle. This is a time to divide and rejuvenate. So this is a very new concept in science, and this has the potential to impact our daily habits. And it has the potential to increase efficacy of medications that we take or supplements that we take on a daily basis. And also what we're seeing now, there are also new drugs that are based on circadian rhythm to essentially based on the idea that as we get older or in many diseases, our circadian clocks are disrupted. And the question is, if we can fix our clock with a new drug, can we also fix a disease? So these are three big principles that are coming into play. And you mention time restricted eating, intermittent fasting.

That's kind of one aspect of this circadian rhythm biology. But this is actually one way to get into the science because once we understand why we should be eating in less than 12 hours and why that has to be consistent, what is the science behind it, then we can dissect a little more into the interrelated parts of fasting, sleep, what time we should be exposed to light, when we should exercise. and that will give strong production of these enzymes and increased acidity to break down food. And then there is a weird thing that happens around sleep time or late at night.

Our stomach is more sensitive. So that means even a little amount of food can hyper. It's almost like the stomach is sleeping and all of a sudden somebody comes and knocks on the door. And not only you wake up, you actually wake up with increased vigilance. you may pick up a steak or something, thinking that somebody is invading. So stomach actually hyper reacts by producing too much acid. And now, too much acid is actually not that bad,

but what happens is too much acid can go up ostefagous and can cause acid reflux. And I told you that how at nighttime, our mouth actually reduces saliva production. The reason is in our sleep we should not be drowning in our saliva. So saliva neutralizes a lot of acid. So then we have increased acid production at night and less saliva to neutralize it. And that's one reason why people eat too late at night, not all, some might actually experience more acid reflux than other.

Right. So now, in the next in digestion is after this stomach is digesting food, it goes to the, intestine and the intestine kind of has a peristaltic motion so that means it beats and sends that food slowly while the intestine is also absorbing nutrient and that process almost starts down during our sleep or late at night so that means even if you have eaten food it actually doesn't get digested doesn't the nutrient doesn't get absorbed later night so this is a clear example how even very basic step of digestion

has a strong circadian rhythm and that helps to make sure that our food is digested right way and the reason why everything starts down in the digestion at night is during the daytime or when we eat just imagine it's a it takes a lot of energy a lot of acid to break down food imagine kind of digesting that piece of sushi that you eat so if you if your stomach is digesting that piece of Sisi at the same time it must be damaging some stomach lining and that actually happens so that stomach lining has to be repaired at night so there is a different circadian rhythm starting from the brain that produces growth hormone and the first couple of hours of our sleep

and although we are not growing after reaching adult adulthood in size or height but actually we are replacing many of our stomach lining and many other cells throughout the body. And that happens only at night time. So again, there is another clock that kind of works with the digestion clock to make sure that during daytime we digest and at nighttime we repair. So these are just very few examples. But if we drill down almost every single cell has its own clock and it has implications for how we should live, how we should organize our day around these clocks. Yeah, it's really fascinating. You know, when you really get a chance to zoom out, we see that the world and the way that nature was set up,

including the 24-hour cycle of the sun and how it interacts, depending on where you're living the body, the sun rising and setting. That was the foundation of what our biology evolved around. Yeah. And now through modern living, we're able to eat later, we're able to microwave foods later. We're able to get processed foods later. And a lot of these foods are way more addictive than they ever were hyper palatable I guess is the right word so we're in a situation where we can see now through your example that just by regularly eating late or late at night or right before bed or midnight snacking as many people do we can now see that things like acid reflux in your example why they could be so prevalent among society right what would be

another example that's tied to late night eating common things that you you see that people are struggling within their body that they may not understand has to do with circadian biology. So one is acid reflux. Another one could be waking up and not feeling rested. Yeah. Is there anything else that you'd want to mention? Yeah.

So, you know, acid reflux and indigestion, another thing we talked about. And again, going back to the same digestion process, one more thing is, you know, when we eat something, most of our food does have some carbohydrate, unless you are just eating ketogenic. diet, which is very difficult to do for long term. But for every irregular person, we consume some carbohydrate. That means that's broken down and that increases blood sugar level and the pancreas has to adjust that sugar by producing insulin. And pancreas does have a circadian clock.

So that means it actually doesn't produce enough insulin late at night. So that's one. And then the second thing is they sleep hormone melatonin. that goes up and night, and that's why people who have sleep problem, they think that they can sleep well by taking extra melatonin, and I'll get to that, but the melatonin actually has another break on insulin production, because melatonin makes the pancreas less sensitive to glucose level in our blood, so the pancreas cannot sense accurately how much glucose is in the blood, so it cannot produce or release enough insulin.

So now you combine these two. What happens is when we eat late at night or very close to bedtime, then there are at least two or maybe even more things that are playing against digesting and absorbing that glucose correctly. One is insulin production itself has slowed down. And second, if there is melatonin that's rising and actually two hours to three hours before our habit. bedtime, our pioneer gland starts to produce melatonin. So that means within two to three hours before bedtime, if we eat, then that melatonin can inhibit, can desensitize the pancreas so that it's not producing enough insulin. So these two can work together to first thing that will happen is you might have higher level of blood glucose level.

And this is something that has been observed since 1970s. In fact, endocrinologist would take healthy people and fast them for 10 to 12 hours and then give them a bolus of glucose either in the morning or after 10 to 12 hours of fasting, the same bolus of glucose or sugar in the evening. What they found was the same healthy person may be diagnosed healthy in the morning, but may be diagnosed as diabetic because this person's blood glucose goes pretty high and doesn't come down easily. So this is another example where people who are thinking

that they can get away with food at night, although we are not walking around with continuous glucose monitor all of us, but some of them. And this is a common theme that we are finding. The third thing that happens is when... And just to make sure I understood that correctly and you're kind of recapping for our audience, so that regular, we're not talking about occasionally people eating,

and the tendency is that at late night, people want highly pot palatable salty sugary types things they want chips yeah which again are types of foods that again that are not you know the ketogenic route right yeah they're they contain a lot of starches starches are broken down as sugars inside your body yeah and not only are you inhibiting your melatonin production which is going to throw off your sleep you're also keeping your blood glucose yeah around higher longer yeah which has all sorts of downstream effects. Yeah, and also since it's the time when insulin products, it's not that insulin

products and it's shut down. It's actually there is a trickle of insulin that comes out and it continues for long time because it has to work hard to get the glucose absorbed. So then your insulin level remains high in the blood for a long time and that has a lot of other effects because insulin also promotes fat making. So our cells actually make more fat also in response to insulin. Right. So that's another reason why late night eating can cause weight gain.

Chronic late night eating. Chronic late night eating. Even if the calories are the same, chronic late night eating could be or is. Is it could or is contributing to weight gain? Yeah. So this is something that has to come from clinical studies. at least in mice or in laboratory animals, where we can accurately control what time they're eating,

how much they're eating, what quality of food they're eating. There we can see that when they eat randomly or eat when they're supposed to sleep, then they gain excess body weight. Yeah, it's so fascinating because then it also helps many people understand how they feel like they're caught in a vicious cycle. Yeah. Because when you eat late at night and your glucose stays up

and your insulin stays up. Again, chronically, we're not talking about the one or two times that people do that occasionally, just to live your normal life that you're doing. You end up in a place where so many things are disrupted in your metabolic health, but then also that leaves you in the morning because your sleep is disruptive that you're more likely to have cravings for sugary, hyper-palatable foods the next day in addition to just feeling not 100%. No, that's true. I mean, a lot of people we think that we can get away with occasional late night eating. And this is where the circadian rhythm, again, some of the concepts of circadian rhythm kicks in. When we think about what are the adverse effect of disrupting our rhythm,

we always think of people who do night shift work, evening shift work, or morning shift work. And there is a rich literature from over the last hundred years, people have gathered a lot of literature, seeing that many people who work late at night or night shift workers, they are actually at a very high risk for metabolic disease, cardiovascular disease, heart disease, etc. Cancer as well. Cancer also. I think I read somewhere that Denmark now will provide extra compensation for shift workers who are diagnosed with cancer because there's so much literature that's there with the association of shift work and cancer.

But I think what is actually disconnected, what we don't understand in real life is, if we ask, what is shift work? When I mean, it's not that. Please break it down. Yeah, it's not that somebody who has, somebody has to have a job, like in police department or a firefighter or nurses. Of course, they are shift workers. Right. But then, if we think about metabolically for our health, for our body, how our body is thinking, whether you're doing shift work or not, because we're, or not because our body is actually not checking whether you checked in to your shift work

or not. It's only checking two things. Are you staying awake for two or more hours between 10 p.m. and 5m. because that's when your body is designed to sleep. So are you up for two or more hours between 10 p.m. and 5 a.m. and 5 a.m. and being engaged in some kind of work. It's not that you're not just lying in bed. your eyes open. Of course, if your eyes are open and you're watching TV, that's also-

Sure. Watching TV or if you're on your mobile phone. Yeah. That's also work as far as your body's because your body is not resting. And so, and if you do that on an average, once or twice a week, that is shift work because your habitual sleep time, suppose, say, is 11 o'clock every night. And once or twice, you are staying awake either till one o'clock. in the morning or you are waking up at three or four o'clock in the morning to get to work or do something and now if we think about it almost 70 80 percent of us are shift worker or we're living the life of a shift worker if you look at the average person who's listening a day yeah because they're disrupted at least a couple times a week yeah they're looking at their phone

they're up for a couple hours they can't go back to sleep essentially they're a shift workers They are a shift worker. Talk to us about sleep debt, how it accumulates, and if people are listening today and they have sleep debt, after you describe it, what can we begin to do? Is it again doubling down and making sleep a priority? So let's chat about a big picture. What is sleep debt? Well, sleep debt is our body needs, for example, seven hours of sleep.

Because a lot of studies around the world when they look at what is the average number of hours people sleep and what are the comorbidities or diseases. or even longevity, what they find is six and a half to seven and a half hours in adults, older adults. We're not talking about college students or high school friends. Older adults. That seems to be the sweet spot. People who sleep less, they have more comorbidities and people who also sleep more.

Maybe they have underlying conditions. That's why they're sleeping more. They also have other comorbidities. Right. You don't want to be sleeping nine hours plus if you're not an adolescent. Yeah. Right? Yeah.

That's a sign that maybe something's going to. on, chronic fatigue, etc. You want to hit that sweet spot of those seven to eight hours. Yeah. So a lot of people who sleep less in the weekdays, say five to six hours or five hours, then they experience it, that their body actually keeps track of how many hours of sleep you have lost so that by Friday or Saturday you are so sleepy that you just want to catch up. When people say, I'm catching up on my sleep, that's exactly what they're doing. their body has calculated and it's telling them that okay so on Saturday you got to sleep another four hours or five hours and they're catching up and what happens is so that's kind of what we say

sleep debt you have taken that debt against your regular sleep and you have to pay it back paid back to your body by sleeping extra when we get older then what happens is a body's the sleep debt calculator doesn't work very well it actually doesn't remember how much debt we are accumulating. So that means you can go with less sleep for five days, but your brain is not remembering, so you'll still end up sleeping less. And you think you're fine. And you think you are fine.

So that's why this is some instances where you should not be listening to your body. if you know, if your smart watch or smartphone is telling you, you have been sleeping for five hours and you know that you are sleeping for five hours every night, and then you got to work on it. Another reason why we also forget our body forget sleep date is when we over-consume caffeine. And this is something I have personally felt because, you know, there are many times when I have to consume excess caffeine or maybe late afternoon coffee just to get through a grand deadline or manuscript deadline or something else.

And then if I continue that, have it in the weekend and also have a lot of caffeine, then of course I'm sleeping less six or less hours. And my brain doesn't remember that, that I am having sleep dead. But the other way it shows up is I'm more hungry, I'm more irritable. I know that I cannot think clearly, and my overall productivity goes down. And I'm kind of struggling. And then I kind of blame myself,

I blame people around me, and I'm thinking that, okay, so for all of my problems, somebody else is responsible. I beat myself, why I cannot get these things done. So a few years ago, I did a simple experiment. I kind of do all types of experiments on myself. One is, I said, okay, so between Thanksgiving a new year, I will stop caffeine, all kind of caffeine-containing drinks.

Coffee, green tea, etc. Diet Coke, anything that has coffee or caffeine, including, you know, dark chocolate also has many flavonores that can keep us awake. And to my surprise, almost every night, the first few days, I felt like I haven't slept for a month or so. My sleep there just kicked back in. And then I would fall so. sleepy, I'll feel so sleepy by a naclock, it was really hard to stay awake past 9.30. And so that goes on for at least 15 to 15 days to three weeks that I'm just sleeping like because you don't have caffeine, you feel more sleepies. Yeah, it means my body is actually has remembered my sleep debt and it's just saying,

no, you got to pay. You have a huge debt and you haven't paid for a long time. And then after two to three weeks, then I come to the equilibrium that I can actually sleep for seven hours. And that's when I realized, okay, so this is my normal circadian rhythm. This is your baseline. This is my baseline. That you want to do a little bit of a caffeine cleanse to reestablish that. To reestablish that.

To reestablish. And also to know what my body needs. And essentially what my body needs is I should be going to bed between 10 and 11 and should be waking up between 6 and 7. That's what I figured out. So this is the kind of stuff that everybody can do. do once in a while, do an experiment. You're not going to die if you stay away from coffee for maybe in the weekend or for a week. And we always talk about personalized health, personalized precision health and all these fancy terms that we say. Whenever that is the word

personalized, we have to keep in mind that more than half of that responsibility is on us to try something, a new lifestyle, try to figure out whether you can change. change the quality, quantity, or timing of your food, exercise, or sleep. And this is where one can actually try. And for older adults, it's difficult because, as I said, even in experimental models, like, for example, we can take little fruit flies. And this is not experiment in my lab, but other people have shown it. And the young fruit fly, if you keep them awake by putting them in a rotating drum so that they cannot sleep. Then the next day, when you give them an opportunity, they will sleep.

But you take the older fruit flies and keep them awake. And next day, they actually don't fully compensate their sleep loss. So this is a phenomena that's already known, happens in humans. So then the question is, can we model it in flies or drosophil fruit flies or in mice? then we can go back and see, okay, so what part of the brain is involved? What can we do for the fruit fly or the mice to remember they're sleep dead so that they can go back to sleep and recover? And then what happens when they have this sleep dead, when they cannot sleep enough?

So for example, now many labs have shown that in experimental condition, if you take a mouse or a fruit fly that is prone to neurodegenerative disease or dementia and you disturb their sleep for a few days, then that can accelerate the progression to dementia, or that can exacerbate the symptoms of dementia. And so that's one part of this story. And then the other part of the story, which relates to timing of food,

is if you now put these fruit flies or mice that are more prone to dementia, and people, we never connect how timing of food connects with dementia, But this is something that actually one of the earliest experiment was, in fact, done in L.A. In Los Angeles, in UCLA. At the Buck Institute? No, actually, UCLA.

UCLA. UCLA, yeah. And what they did was they took a few mouse strands that are more prone to Huntington disease, and they did eight hours time restricted feeding. So that means these mice have to eat only for eight hours and fast for 16 hours. And what they found was, surprisingly, the sleep quality of these mice actually improved. And I remember that experiment because the researcher and their team actually asked me, hey, do you think there will be an effect?

And those are the early days, 10 years ago, nine years ago. And I was thinking, huh, this will be an interesting experiment to do. Let's try it. He tried it. And we found that. And then now there are a lot of studies on how time-restricted feeding or intermittent fasting actually helps brain health by improving sleep. And this is something that we had never thought.

So just by narrowing that window, not eating late, right? Which we were talking about earlier. Which typically is going to mean that if a lot of people are falling to sleep at 10, you're done eating by about seven, six or seven, because you want those three hours that are there. again, that goes into all the circadian biology of the organ systems, everything like that, but you're also saying that in addition to not keeping your glucose and your insulin high, there is an improvement in the brain potentially as well too. Yeah.

So this also relates to another question that I often get. People say, well, I'm healthy. I already have the perfect body composition, and why should I pay attention to when I eat? And my answer is, well, we know there are few things. One is, even though you are healthy, one thing is it can actually keep your brain health much better. And in fact, when we did our first study on humans, and this was eight years ago, 2015, the people came out. And there are only eight participants in their study. And this was very early days, we asked, is it feasible for people who have been eating for long time?

throughout their life last 15, 20, 30, 40 years, can they change that habit? Because this is a big issue and behavior change. Sure. Because we are so married to our old habit, Vince, imagine, even for coffee, means a lot of people, they cannot give up coffee. It's not that they're born with a coffee

in their sippy cup. We picked it up along the way, but we got so used to coffee that we cannot leave it. So similarly, people who are used to snacking over a long period of time, the question is, can the change behavior? And in that study, there are only eight people. And again, this was funded by an innovation grant from the Salk Institute by a philanthropist.

And when these eight people, they stuck with 10-hour time restuating. So that means they were allowed to eat for 10 hours. They self-selected that 10-hour window so that that fits with their lifestyle. And they had to do it only for 18 weeks. And that was the advice that, okay, so we'll do this study for 18 weeks. At the end of 18 weeks, we'll collect some data, and then you are free to go. And so they were free to go after 18 weeks. They were not even obese people.

They're mostly overweight BMI somewhere between 25 and 30, and the average BMI was 27. And they lost a modest amount of weight, 3.5% body weight. We didn't actually measure at that time body composition, whether that is fat loss or muscle loss because it was a pilot feasibility study. But what was interesting was after a year, we were curious because in many behavior intervention, people actually can't change their behavior forever. It's not sustained. It's not sustained.

And in fact, people who do weight loss trial, they try to reduce calories, change a different diet plan or get on a diet. they actually gain back a lot of body weight that they lost. They will, many of the benefits actually disappear. So that's why we are curious. We asked them to come back after one year, and then we realized that to our surprise, they actually kept that weight loss. Even though it was a small weight loss, we thought that they would gain back that weight.

They kept that weight loss. And we are curious. So we had a very standard questionnaire about their daily habit and other stuff. And what was surprised to see was they said all of them, they said it improved their sleep. They were less hungry at bedtime and they're more energetic in the morning. And they said the reason why they continued with the habit was not because of weight. It was because how they felt, how they were feeling that they were working at a higher performance level throughout the day. And that's the first time. This is where human studies are so important.

because when we are studying fruit flies and mice, we cannot ask the mice and fruit flies, how are you feeling this morning? Right. And the mouse is not giving me high five. Yeah, and with the fruit flies and the mice, they also don't have free will to choose how much food they want like human beings do.

Yeah. So this was the power of doing a human study and then following up with the individuals. Yeah. And another thing, the difference between human and mice is actually we did an experiment where the mice had to eat nine-ups, nine hours Monday through Friday and then we get them a cheat day, weekends for cheat day,

so they were allowed to eat whenever they wanted because the food was given 24-7 on the food helper and they did not, they actually don't learn the habits. So that means they continue to eat 24-7 in those two days, they over it. The good thing is they still had a lot of health benefits, almost 80% of health benefits. From practicing the time restricted eating. just for five days. For five days. In mice. And that was actually eye-opening for me

because I thought that all these benefits will go away if they cheat for two days. And because, you know, when these mice are eating randomly, then they're also disrupting their circadian rhythm and other stuff. And that gave me hope that even humans, hopefully, if they eat, if they try to do time-resuiting, even for five to six days, that can have health benefits.

So that key experiment in mice give us hope. But in humans, it's very different. When we talk to people who have been trying, and most of our studies are 10 hours time receiving, I'll get back to Y10, 0.8, not 9, 9, 6, etc. They say that they get food hangover if they eat late. And this is something that our mice never told me. And then, again, a lot of people,

they actually, when I think of hangover, it's mostly alcohol. Right. But then I came to understand this from people's point of view because they said, well, food hangover is when you eat late and when you wake up in the morning, you feel like the food is still there, it's not digested, and you feel groggy, and you don't have appetite to eat, and your whole morning is spoiled. And it's almost like a hangover from alcohol, but it's from food. And we realize there are a lot of people who actually try this.

If they eat late into the night, their body revolves and they remind them, hey, these are the immediate bad things that you'll face. So that's something that we realize that in the human studies, that time-restritating has an impact on sleep. Again, we don't know why. Because sleep researchers essentially study sleep. Right. Nutrition researchers don't ask questions about sleep. Sure. And this is a challenge for people like me because when we want to do a experiment and most listeners, when we think about health, we are not thinking about only how to improve sleep or how to improve exercise or how to improve food. In a day, we always think about all three aspects.

and it's very challenging to measure, objectively measure all this stuff, even in mice. Forget about humans. We are not talking about humans. Totally. Yeah. So this is where combining mouse research and human research actually helps us to go back. Now we know that, okay, so it improves sleep. Then we're going back and asking, okay, so what happens?

Now, people who do time restricting or mice that do time resty eating, do they, does their brain remember that sleep date when they get older? And that's a very fundamental question that we're trying to figure out in basic research. And then we go back and ask the same question in humans. As such a panda described, our daily practices, whether they be our sleep routines or eating habits or even the timing of when we eat, have the power to align with or disrupt our body's natural circadian rhythms. Now, let's turn to my conversation with Dr. Martin Mord-Ead to understand another key factor

impacting our circadian rhythms, modern lighting, and specifically the pervasive blue-rich LED lighting that's wreaking havoc on our health. But don't worry, there are things that we could do about it. Let's tune in. One of the most damaging things you could do to yourself and your health, especially if you care about living a long healthy life, is sleeping with the lights on, which you mentioned that a lot of elderly people do, or there might be situations where people have the TV very bright in the background on all night.

And that is a very damaging thing for your body's natural circadian rhythm. Yes. And the secret about this is, I mean, number one, you know, people like him, little bit of light to avoid trips and falls and things like that in the bedroom. Okay. But if you direct the light down at the floor, not with your eyes, and if you make that light an amber orange light that has no blue in it, that you can have potentially a little bit of a light there. But yes, the typical bedroom lights, and these days, anything you buy, the TVs, pump out this blue rich light. Any light bulb you buy is mostly, you know, 98, 99% of it.

center of them are blue rich. And that's going to change. There are now, the solutions are out there. The solutions that we can use are out there. But essentially, it is something, I think it's largely related to people's anxiety and they like the lights on. In fact, here I am, we're sort of expert on this whole thing. And I go on trips and speaking trips and conferences and all the rest of it. And I'm not talking my wife the other day, and I said, what do you do when I'm out of town? She said, oh, I always speak with the lights on. I was horrified. And so I preach you to her as much as everyone else, right?

And now I think she understands that you've got to have those lights off at night. Or at least, as you've mentioned, which is what I've done for my wife, who likes to sleep, or at least have a little bit of light on when I'm out of town, get one of those amber red lights. So we have those bulbs all throughout our bedroom and a master switch that she can turn them on and still feel that she has something on, but she's not getting that toxic blue light in the evening. That's right. And if you've got a clock in the bedroom, you know, make sure it's a red clock, a red LED clock, not a white or blue LED clock.

So, yeah, all those things. You know, you're one of the world's authorities in this area and you have a fascinating background. We're going to get into your background in a little bit. But as I read your book and started to understand this narrative, the story gets deeper and deeper. And it's not just about our toxic exposure to blue light in the evenings. And again, you've said blue light is neither good nor bad. It's about the time of day that we're being exposed to it. And the chronic exposure of it that is linked to increased rates of, you know, snacking and obesity, insulin issues.

as we've mentioned, cancer and even lifespan in some aspects as well, too. We're going to talk about that in a second. But the secondary part of the story that I just want to mention here for everybody who's listening is it's not just about the toxic blue light. It's also the fact that we are living a life chronically indoors, which means that we're not getting healthy exposure to the sun. Can you talk about that for a moment? Absolutely.

the critical second part of the story, it's the, you know, one side you've got excess light, excess blue-rich light during the nighttime hours, but the equally important part of it is our lack of exposure to bright blue-rich daylight. Now, we spend over 90% of our time indoors these days. We have in the, and when we're indoors, we're living in light levels that are typically 300, 500 lux, that's a measure of how bright light is. Now, take 500 lucks, which is the brightest indoor light we normally see, and you walk outside the door and you go outside, on a dim day, you're getting 10,000 lux, on a cloudy day, 10,000 lux. And if it's a bright, sunny day, you're getting 50,000, even 100,000 lux of light. So the amount of light we're seeing is incredibly small.

So one of the most immediate things everyone needs to be advised is get out in the daytime. And people who get out in the daytime and don't stay indoors all day live longer, are healthier, have less heart disease, less diabetes, and so forth. So it's a very strong effect. The other interesting feature of that is that it actually the time of day matters. And a fascinating studies have gone on looking at because one of the, one of the conditions we haven't talked about, is psychiatric illness, depression, anxiety, PTSD, all the whole cluster of illnesses that are 30% higher in people who are exposed to light at night and 30%

lowering people who get outdoors regularly. But take the classic case, this is a really mind-blowing study, if you look at people who admitted to a psychiatric ward because they've got severe anxiety, depression. And you put them in a hospital, and half of the room in the hospital are facing south and east, in other words, they see the morning sun. And the other half are facing windows are facing north and west. Those that get in the rooms, same pharmacological treatments, same physicians, same therapy, get out of hospital half the time when they see the morning sunlight, as opposed to not

getting in the morning sunlight because they're in those western north facing rooms. Staggering finding, and that's just like coming in through the windows. That's not even like getting outdoors. So there is something very fundamental we've lost by going indoors. You know, the evidence base that you highlight inside of the book is, as you mentioned, it's mind-blowing. You know, you talked about a particular study that happened among Swedish women. And I'll just, I'll read from the excerpt from the book that's here,

because this ties in together an important concept. I'll read it and then I'll talk about that. So you mentioned that a study of 29,000 Swedish women aged 25 to 64 years, followed prospectively over 20 years, showed that sunlight exposure greatly reduced deaths from cardiovascular disease and other non-cancer illnesses such as diabetes, more than offsetting any risk from skin cancer, And now my commentary is that, you know, as we've said, this is about getting toxic blue light at the wrong times of the day, not getting enough natural light from the sun, which we were designed and evolutionarily have been raised on this earth to expose ourselves to. And then there's this message that's out there of people saying, don't spend time in the sun. You're going to get skin cancer. Tell us why that's not the right way to look at things.

Well, the fascinating thing about that study that was done in Sweden by Professor Lindquist and his team, fascinating part of it is they never were intending to look at, they had an assumption. And the best studies is when you start out with an assumption that proves to be totally wrong, they thought they were going to study how much more malignant melanomas were developing Swedish women who spent time outdoors as opposed to those were indoors. They were going to track that. and they found, indeed, there were more melanomas and other skin cancers in those women who were spending time outdoors, but they lived far longer, the staggering thing, and they were healthier.

And this actually goes back to explain some rather curious findings from years ago, where they looked at sailors in the US Navy. Now, if you're a sailor out in the US Navy, you've got a lot of exposure to sunlight out in there, on those ships. And they looked at them. And gosh, those sailors developed eight times more melanomas than the average population. But they all lived longer than the average population. So basically, yes, skin cancer is a problem.

And yes, there are people die of malignant maloloma. But far bigger risk is staying away from the sun and staying away from daylight. Now, one of the key things here is where the light is coming. For these biological effects, a lot of it can be done through the eyes. You don't have to expose your whole body and risk your skin all over being melanomaids, skinning out and your eyes being exposed to bright light that does most of the trick. But it's fascinating because it sort turns upside down some assumptions. And so it's really a very interesting part of this whole thing that we now understand.

understand how potently positive is daylight and sunlight during the day in a way that we've so, you know, rather dismissed with our modern live-indore society. So when it comes to skin cancer, if I'm understanding correctly, we don't want to be on either one of the extremes that are there. Some dermatologists that are out there, especially on social media these days or podcasts saying, avoid the sun like the plague. And then the other extreme side of it, which is, hey, get sun all day long and don't be smart about it. We want to be somewhere in the middle, which is you can be smart about it and get the benefits that come from being outside and exposing yourself to a healthy level of sun,

and you can still protect the rest of your body. Yeah, and the key thing is the morning matters, and before the sun hits its, you know, reaches its zenith, the peak in the middle of the day, you want to go out in the morning and relatively early in the morning, you know, in your day. that provides the strongest circadian clock resetting signal that keeps your body in sync most effectively. And it's probably about an hour or so of light that you need, ideally. You don't have to be out for hours and hours. But that is hugely important.

So get out for that walk. Get a dog if you can't find an excuse to get out. Take your dog for a walk. But getting outside every day in the morning, regular time. And regularity is also one of the key things in terms of health, too. and particularly exposure to light. So one action item and an immediate takeaway from this interview is upon waking up, ideally, you know, we've heard different things.

I've heard Dr. Andrew Huberman talk about, you know, ideally in the first 30 minutes of the day, try to get outside, you know, upon waking and get that exposure to that morning light. Is that generally your recommendation as well? I wouldn't go that far because the problem is that then the resetting of our biological clocks are most sensitive in the mornings. But if you go to, if you take that too much to extreme, particularly during summer hours, you'll be nudging yourself towards Europe time

if you're living in the States by early morning light exposure. You get yourself out of sync. So I think you can have breakfast first and then go out. I don't think you have to get out in the very first 30 minutes because otherwise you will actually be resetting yourself, you know, in an eastward direction. And you're going to end up in mid-Atlantic time or somewhere in Europe. So have some sense of regularity with your schedule, you know, waking up around the same time.

Obviously, there'll be some seasonal variability. But in general, when you're ready, after you have your coffee or your breakfast, go outside and spend at least, if you can, maybe 10, 20, 30 minutes outside. But you're shooting for a total of about an hour of being outside a day at a minimum. Is that to be understood? That's right. And a good brisk walk or a run is, you know, helps your health. And, you know, one of the interesting anecdotes is that golfers live longer. You might say the non-golfers.

And you could say, well, you know, maybe that's probably that, you know, if you get around a golf course, that's going to take you an hour or two. That's a way of getting a heavy dose of natural light. This all points to the fact that we have to be extremely intentional with our light. environment. The same way that many people here are thinking about the food that they're eating, are conscious about not over-consuming calories, are trying to do their best and choose organic and stay away from maybe some of the harshest chemical pesticides that are out there. In that same sense of diligence that we have in what we put in our body, we have to bring

that diligence to light because our health literally depends on it. I want to switch topics for a quick second here. And I want to go to the topic and the connection of blue light and obesity. What have you found out through your years of looking at the literature that's out there? Well, we've done a lot of looking at the literature, and we've also done a lot of studies now, both in the lab, but also in the workplace. And what's really interesting is when you look at people who are under blue-rich, that means standard LED, standard fluorescent lighting at night, they are number one, they have more hunger, they have a higher appetite. They actually snack in the workplace twice as many snacks on the night shift than if you give

them light that doesn't have any blue in it. So there is an appetite part of the problem. Then there is the fact that if you look at the insulin glucose axis, in other words, metabolic measures, and you test like, a glucose torrents test, for example, where the standard test for diabetes, where you drink a bottle of sugar water, and then every half hour or so the doctor takes a blood sample, and they track how the insulin glucose and insulin levels rise, and then they fall back down if you are healthy, back to normal levels by the end of two hours. If you've got diabetes, those levels climb

higher and stay higher, we find that when people are under regular LED lights, the standard LED lights, conventional lights that you buy in the store, that they get pre-diabetic, even the first, perfectly healthy person in the first night of exposure. And so by the morning, they've got a abnormal, a diabetic-type glucose torrents test. And so we're adjusting, we're having big effects, therefore, on the fundamental method methods of not only snacking, but also how substances are metabolized in the body. And, you know, you're creating this metabolic syndrome, you know, in real time just by being exposed to blue rich electric lights. Let's pull on a thread for our audience of a little bit of how are all these

things happening from being exposed to the wrong light at the wrong time. And specifically, I'd like for you to unpack the idea of this master switch that's in the brain that you were a big part of the team of helping us discover. Can you talk about that? Absolutely. The circadian rhythms of our body are all those functions of the body that go up and down with the time of day. So cortisol peaks, for example, just before dawn. melatonin peaks at 2 a.m. in the morning. Other rhythms, growth hormone peaks just when you go to sleep. There are all these rhythmic patterns of body temperature goes up and down. They're all called circadian rhythms. They are not products just simply of our environment and what we're doing on outside and what we're doing.

They're actually driven by a master clock in the brain and then lots of clocks, millions of clocks in every cell and tissue of our bodies. Now, that was, first of all, you know, studied in animals, but when I came, when I first started in the field, it was assumed, in fact, the leading scientists at the time thought that humans did not have a master clock. It's called the superchismatic nucleus, by the way, a SCN for short. The acronyms are useful because of a mouthful. And the supercosmatic nucleus was found in various animals. It was found in 1972 in rats and in hamsters, but no one could see it in the human brain. And one of the things our team did was one of my postdocs actually

realized that when you're looking at atlases of the human brain, that they are showing you every 50th slices of slice of the brain and throwing out 49 slices in between. So you're only getting a sort of a snapshot of one slice through the brain, and they slice it through it systematically and show it as a map. But if there's a small entity like this superchaismatic nucleus, then you're going to miss it. So Ralph Leidick, my postdoc, went back and looked at all the 49 slices in between, and lo and behold, consistently there was this same structure that was seen in rats and hamsters

and monkeys and elsewhere. So, yes, humans did have a super charismatic clock, wired in the same way with a pathway coming back from the eye, from the back of the eye, from the retina, through a so-called retinohympathymic tract, which lit direct pathway into this super-casmatic nucleus. And given that that clock is the fundamental thing that keeps everything in timing, that's a really fundamental part of the system. Now, I mentioned millions of other clocks. The problem is if the master clock is not being adequately synchronized by bright blue light during the daytime and abscess at night, then it gets out of sync and the signal becomes weak. And the various functions of the body all start getting out of time with each other. And I've likened it to a discordant orchestra.

If the conductor is not guiding the orchestra, the conductor being the S-D-N clock, then, of course, you get this really discordant sound. For the body to be harmonious and to be healthy, everything needs to be tightly in sync and with a robust amplitude, in other words, a strong beat to this system. And you only get that if you're exposed to bright daylight during the day and pitch darkness at night. And that gives you this strong beat. And that is the thing that keeps your body healthy, gives you a long healthy lifespan, boost your immune system, protects you against viruses and COVID and everything else. All those things are elements are a key element of health that we've too often neglected just because of a comfort of sitting indoors in a comfy situation and working half the time in front of a computer screen.

I've heard you mention that the evidence is so robust and there's so, so many people that are contributing to the literature in this field of understanding the exposure of light and how it impacts our health. I think you mentioned that there might be 30,000 researchers that are out there that are working on this. Then we have the mechanistic implications and the ways that it works inside the body. You know, you and your team have been a big part of that. There's been other teams that have been working on that too. We have all these studies that are out there. We know the dangers in the body of literature. And yet, Many of my audience members are probably scratching their head thinking,

why is this the first time that I'm hearing about how dangerous blue light at the wrong time of day is to my body, so dangerous that it could be increasing my risk of breast cancer, obesity, worsening my immune system? How come no doctors or public health individuals are talking about this important topic? Great question. One of my colleagues said it very well.

He says the problem is the scientists in this field just talk to each other. They don't talk to their neighbors. So this is well-known science. In fact, I did a consensus study with 248 of the world's leading scientists in this field recently. Just to make sure we were all on the same conclusions. And indeed, we came out some very solid conclusions, consensus among these scientists. The blue light was the key. It's detected by melanopsin, this pigment in the eye.

It's synchronized in the circadian rhythms, that diabetes, that cancers and everything else are related to disruptions of this system. All that is well-known, established science, but it just is staggering to me and others in the field that this has not yet penetrated the public consciousness. And it should because this is – we're talking about it. environmental pollutant, a blue light at night. Yet it's the simplest of all the environmental pollutants you can think of. We talk about P-FAS chemicals and we talk about microplastics, and we talk about all these things, horrendous problems to clean up. This is pretty simple. Just change the down

light bulb. It's actually a pretty simple solution. And yet there is a lot of, and you might say, Why is that? Well, there's a lot of embedded interest in their commercial interest in the industry. They've built these lights. That's what they sell. It's a 150 billion dollar industry that's like a, you know, an aircraft carrier. It's hard to turn it around sometimes. It is a industry that is being regulated by the Department of Energy, which has put its head quite frankly. frankly in the sand about this issue. And, you know, they have refused to accept and understand that this is a real issue because their focus, their mandate is to reduce the lumens, or at least to maximize the lumens per watt efficiency.

And let me explain that a little bit. Lomens is a measure of the amount of light, but it's not the measure of the amount of light per se. It is the measure of brightness of light. And because of the way the eyes processed light, it is actually looking only at the green and yellow wavelengths in light. It's not looking at the blue, which is essential for circadian health. It's not looking at the red wavelengths in light, which is essential for healing and a lot of important health issues around red light. They purely measure this brightness of light.

And so they're actually not measuring the healthiness of light. They're measuring a convenient standard that engineers can get their head around. You know, let's just make this LIMSPo-Watt standard as high as possible. And that way, we force out and now are ban, banning effectively, all incandescent light bulbs. Those are the standard old light bulbs. We banned all halogen light bulbs. We're banning all fluorescence. And now we're forcing the consumer to only have these LED lights.

and the LED lights that are pumping out this energy-efficient light, which is rich in blue, because that's the way you can get the most efficient conversion of electricity into lumens. So we've got ourselves into a sort of situation where we are harming ourselves. And you might say, you know, okay, it's all about the good of the climate, good of the planet. And we all recognize the importance of global warming and curtailing that. We all recognize the electricity consumption is part of that. We all recognize the problem of greenhouse gases. But you cannot fix that by creating a huge human health problem,

which is far bigger in its effect right now than the current effects of climate change. So it's really a matter of getting the balance right. And this is a huge issue. But as I say, these ingraties these, these, these, forces are there, and also the inertia of the market. If the consumer doesn't understand it and isn't asking for blue-free, zero blue light at night, then the lighting companies won't build it. And the lighting companies say, well, let's have the consumer ask for it, but the consumers don't know. And the energy people are trying to regulate it so you can't get low-blue,

I mean, the incand-escent relatively low in blue light, you can't get them anymore. So we got ourselves in this situation, one of the reasons I'm writing in the book, is trying to break through this logjam of misconception, inertia, and quite frankly, misinformation in some cases. One of the saddest things that we see today is that in the Western world and increasingly around the rest of the world, as they get access to modern health care, is that when people are sick from food, but also things like chronic poor light exposure, not enough sun, etc. And these things materialize as chronic disease as we age, they get sent to the hospital. And the hospital is an environment that has often the worst lighting in the world for the people

that are the most vulnerable. Can you talk about that? Absolutely. Yeah, this is the problem. The hospital lighting is typically and historically, it's all been blue-rich fluorescent lighting. That's what I, when I was a surgeon in training, that's what I worked under 24-7. But also now more and more LED lights. It's all about meeting, you know, energy efficiency standards and, you know, having certifications like what's so-called lead stat, lead certifications that they can boast about, about how health, climate-conscious they are. But amazingly, they haven't got it yet, and it is a hard sell to get people to start to change. So yes, healthcare is one thing. And yet the evidence is being very strong. I mean,

in other words, in Europe, they're rather far ahead. There's companies in Europe that are putting lights into nursing homes, circadian lighting, which is free of blue at night and rich in blue during the day, in nursing homes, in hospitals, showing a lot of beneficial end results. But it is slow to catch on. And, you know, as I say, that's part of the reason of getting the book out is to try to get this breakthrough here. We've got to get to the tipping point where when people start demanding it, then these lights get in because then, and people need to know what to ask for specifically so they

can't be, have placebo lighting passed off on them. Since becoming aware of how detrimental blue light can be for quality sleep and our circadian rhythms, I've personally been on a very serious journey to reducing my exposure to it. A big part of that has included implementing Dr. Martin More Eves' recommendations to especially avoid blue light exposure in the evening and at night and instead use amber or red lights, or at least if you don't have those dimming the lights around you and turning off the overhead lights. I've also, personally, I've invested and I've got my wife invested into some high-quality blue light blocking glasses and leaned into routines that expose me to natural light throughout the day, especially within the first 20 minutes of waking up.

And as you heard from both Dr. Suchin Panda and Dr. Martin Moreyed, there are many very important yet simple day-to-day things that we can do to make sure that we are doing our best to optimize our body's natural circadian rhythms. So as we venture into the new year, and as many of us are looking to double down or implement new behaviors, I hope that today's episode offers additional motivation to make sure these simple things that are often overlooked, like supporting our body's natural circadian rhythm, get the love and attention we deserve, that our bodies deserve. If you want to listen to any of the full-length interviews that we had featured a Dr. Suchin Panda, Dr. Martin Moree, you can

find a link to those in the episode show notes below. And if you like today's episode and you want to inspire somebody, send this episode to a friend who's super commuter. to being in the best health in 2025. What they learn in this episode might get them motivated to double down on the basics that often lead to so many of the long-term results that many of us are looking for in our life. Until next time, Drew Prod, signing off. Thanks for tuning in.