ANEW Insight

Longevity, Metabolism & Mood: The Science of Circadian Health with Dr. Satchin Panda

• Dr. Supatra Tovar • Season 1 • Episode 113

Share episode

Send us a text

Circadian rhythms and metabolic health aren’t just abstract science—they’re daily forces shaping your energy, weight, mood, and longevity. In this episode of the ANEW Insight Podcast, Dr. Supatra Tovar and Dr. Panda explore how sleep, light, and eating schedules align with our body’s natural clocks to repair tissues, detoxify the brain, and prevent chronic disease.

🔑 What You’ll Learn in This Episode

  • Why sleep is the body’s nightly “repair shop” for skin, gut, and brain.
  • The discovery of light-sensing proteins and their impact on circadian health.
  • How every cell in your body—from hair to intestine—follows its own clock.
  • The truth about “night owls” vs. morning people, and how lifestyle shapes habits.
  • Simple daily practices to align light, food, and sleep for long-term vitality.

🕒 Timestamps

  • 00:00 – Welcome & introduction to Dr. Panda’s groundbreaking research
  • 02:00 – How circadian rhythms influence energy, weight, and aging
  • 05:00 – From plants to humans: the biology of internal clocks
  • 08:30 – Discovering light-sensing proteins and their health impact
  • 12:00 – Why circadian rhythms evolved as survival mechanisms
  • 16:00 – Sleep as the ultimate reset: brain detox & tissue repair
  • 20:00 – The night owl myth: habits vs. true genetic differences
  • 26:00 – The role of light exposure and sleep in mental health
  • 29:00 – Food timing teaser: why when you eat matters most
  • 31:00 – Closing thoughts and preview of Part Two

📚 Continue Your Journey

👉 Subscribe to the ANEW Body Insight Podcast for more conversations bridging psychology, nutrition, and wellness.

#circadianrhythms #metabolichealth #sleephealth #brainhealth #energybalance #longevitytips #lightandhealth #chronobiology #mindfulnutrition #bodycl

Thank you for joining us on this journey to wellness. Remember, the insights and advice shared on the ANEW Body Insight Podcast are for educational and informational purposes only and do not constitute medical advice. Always consult with a healthcare professional before making any changes to your health routine. To learn more about the podcast and stay updated on new episodes, visit ANEW Body Insight Podcast at anew-insight.com. To watch this episode on YouTube, visit @my.anew.insight. Follow us on social media at @my.anew.insight on Facebook, Instagram, TikTok, and Threads for more updates and insights. Thank you for tuning in! Stay connected with us for more empowering stories and expert guidance. Until next time, stay well and keep evolving with ANEW Body Insight!

dr--supatra-tovar_3_07-30-2025_111119:

Welcome everyone. I can't even believe my luck, but I am so honored and so fortunate to have world renowned scientist and bestselling author Dr. Satchin Panda with us today. Dr. Panda, thank you so much for joining me today.

satchin_1_07-30-2025_111119:

Yeah, you're doing great in communicating science to general audience. You know, we, scientists are not very good in telling people what we do, so thank you for doing this. His pioneering discovery of the blue light sensing protein. Melanopsin helped explain how light regulates the brain's master clock and has influenced global recommendations on sleep hygiene and screen use. I know I have changed my screen use based off of this research. Dr. Panda is also celebrated for his research on time restricted eating, showing that when we eat.

dr--supatra-tovar_3_07-30-2025_111119:

The Diabetes Code. Uh, Dr. Panda has brought the science of biological timing to the public in an accessible and empowering way with warmth, brilliance, and unwavering dedication. He continues to shape a new era of health, rooted in the rhythms of nature.

satchin_1_07-30-2025_111119:

Yeah, that's a very loaded question that goes back to 30 years or so. But, um, you know, when I was finishing college and starting to think about what to do in life. I was drawn into biomedical research, but at the same time I realized that biomedical research, typically we compare the body to a machine or a car and just like you can start the car or start a machine. At any time of the day or night, it'll still run the same. body is not like that. Um, if you ask me to give, do this podcast at uh, one o'clock and night, then there is no way I'll be awake and talking to you. So that struck me that our body is not the same between morning and evening or when we go to bed. We go to bed in one state, very tired, and our brain is very confused and foggy, and we wake up very differently if you had good night of sleep.

dr--supatra-tovar_3_07-30-2025_111119:

So give me a picture of how your research began. Like what did you first start to look at, and then how did you, um, discover these, uh, light sensing protein

satchin_1_07-30-2025_111119:

Yeah, so my, uh, undergraduate research was an, uh, undergraduate degree is in actually agriculture or plant biology. And, um, most people may not know that plants also have a strong circadian clock. And those who have seen the video of a sunflower plant can appreciate it. Like, uh, the sunflower leads wake up in the morning, harvest the light, and then the sun sunflower kind of tries to look at the sun and then. At night, the sunflower lips actually drip down as if they're going to sleep. So, and that process actually helps plants to harvest sunlight and increase the eff efficiency of, um, carbon fixtures on, on making food, making all the food that we eat ultimately comes from plants and that increases. Having a clock actually helps the plant to of open the shop before the sunlight comes in and then they shut down the shop before sun sets. And my interest was how the plant has a clock. So I was working on a mutant plant that actually had a slightly longer clock. And the bottom line is after I cloned this particular gene in the plant, we realized that this quote unquote clock gene was actually tied to NAD metabolism that means to energy balance in this cell. So that was a aha moment that, well, actually, the biological timekeeping is really linked to how the plant is sensing energy, making energy or storing energy, all of that. As plants, um, always have to sense light as also prime to the idea of how humans or mice sense light and reset our clock. And until that time, it was known that our usual rod and cones that we have in our eyes that give us vision so that we can navigate throughout day and night. Those rod and corn cells are not necessary for resetting our clock. So that means there are many blind people who cannot see, when they fly from west coast to east coast or vice versa, then they do get their flag for the first three or four days and then they can reset to the same time zone just like rest of us. We get a tan you know, vitamin Bs produced in our skin in response to light. None of that process seems to be sufficient to reset our sleep work cycle. So that's why I was curious in that eye that is not rod and cone that restart our clock so that lead to the research, and this is where I must also emphasize how foundational research actually helps make big breakthrough. cells, and opsin typically refers to a light sensing protein. So that's how it was called melanopsin. So it does not me, but some other people who were curious about how frog gets a suntan. They figured out that there is a licensing protein called Melanopsin, and this is one example of how foundational research funded by honest taxpayers actually leads to some discovery and then another stream of foundational research that was trying to sequence the genome of humans so that we know what genes are also at the same time genomes of mice, flies and all these organisms that is going on. And then we figured out that this gene that makes a frog get suntan is actually present in very few cells in human eye or mouse retina and these few cells, and not the ones that we use to see the world, but cells were never known to have a light sensor. So this is an example of how very foundational research in two different completely unrelated fields, genome or DNA sequencing and how frogs changed. The skin color came together and we discovered that this gene is there. That is an amazing, uh, interconnection of species and studies. Um, I am so grateful to the sun tanning frog and that little jet lagged mouse. So we, um, not only we humans, almost every living, moving animal, and also almost all plants on this planet have what we call a circadian clock. Circadian literally means 24 hours clock. And the reason is, um, if you now go back to uh, our ancestral leaving, for example, you know, once I was in Africa and I realized the importance of a circadian clock because, supposedly there is a overcast day, it's cloudy and all, and then you are hunting or gathering food outside it becomes late afternoon and, and you're kind of a little bit hungry and you want to come back home. Because you know, being out there among lions in the evening is not the best thing for your survival, you run back to your hut. And, and actually that's what, uh, literally happened to me because I was trying to get back to my campsite and I got lost. And I realized that, huh? That primal fear came like, is there a lion in that bush is going to attack me? Because lions actually come back. They know that. This is the time when animals and humans, not humans, animals get lost. And this is the time when they come to drink their last sip of water. So this is the time when to attack. the idea is my circadian clock can sense that evening is about to happen and I, I have to go back home, eat something, and then go back to sleep is a very survival advantage. Forget about me. Supposedly it was a deer or a little rabbit. All of them do it. So circadian clocks essentially let us anticipate time and then start to do something before that time arrives. For example, in this case, I anticipated when it's going to be dark and then I ran back. So similarly, what we have discovered is means when I say we, it's the entire field of circadian rhythm. Hundreds of scientists over the last 20, 50 years is we have very intrinsic time counting mechanism that's built into our DNA, literally into our DNA. So that means if you now lock me inside this room without a watch, without a clock, without internet, without phone, there is enough food here on the bed, then, even without knowing what time it is, my body will fall asleep, will feel sleepy around say nine or 10 o'clock in the evening. I'll sleep for eight, nine hours and then wake up even without any external cue of day and night cycle. I'll wake up exactly after eight hours or so. Uh, my body temperature will begin to rise. I'll have bowel movement, mostly likely in the morning, my cortisol will peak, and then the, I'll feel like, um, eating something moving around throughout the day. And then in the evening, again, this. I'll go back to sleep and it'll continue to happen in this clockwork mechanism like five or 10 minutes precision every single day. And in fact, these experiments were done long time ago, almost 60, 70 years ago. Some volunteers wanted to see whether the circadian clock, they actually went inside a cave and then everytime they went to bed, they had a home telephone they would call outside saying, I'm going to bed. then the outside person will write down what time it is or, so they did that sometimes in the care of spending 60 days, 70 days, without any contact with outside ward, without any time in queue. Hundreds of scientists over the last 20, 50 years is we have very intrinsic time counting mechanism that's built into our DNA, literally into our DNA. So that means if you now lock me inside this room without a watch, without a clock, without internet, without phone, there is enough food here on the bed, then, even without knowing what time it is, my body will fall asleep, will feel sleepy around say nine or 10 o'clock in the evening. I'll sleep for eight, nine hours and then wake up even without any external cue of day and night cycle. I'll wake up exactly after eight hours or so. Uh, my body temperature will begin to rise. I'll have bowel movement, mostly likely in the morning, my cortisol will peak, and then the, I'll feel like, um, eating something moving around throughout the day. And then in the evening, again, this. I'll go back to sleep and it'll continue to happen in this clockwork mechanism like five or 10 minutes precision every single day. And in fact, these experiments were done long time ago, almost 60, 70 years ago. Some volunteers wanted to see whether the circadian clock, they actually went inside a cave and then everytime they went to bed, they had a home telephone they would call outside saying, I'm going to bed. then the outside person will write down what time it is or, so they did that sometimes in the care of spending 60 days, 70 days, without any contact with outside ward, without any time in queue. So, for example, you cannot eat and swim and read at the same time, or sleep. What we call a body has figured out a way to do incompatible processes at different time of the day. So that's why we sleep. We don't have bowel movement in our sleep or we don't have, Yes, we had to work for it, but actually you have to just press now home delivery. So, uh, you know, so this compatible processes that together incompatible processes are differently. And then the third thing is, throughout the day when we do certain tasks, our body actually goes through a lot of injuries. So for example, our gut lining, nearly seven to 10% of our gut lining gets injured uh, our skin cells get injured. So there are a lot of injuries that happen during the day and. I if, if you imagine if there is a machine like that getting this much injuries, then you have to send that machine or your car to the body shop to the repair shop to get it repaired. That's exactly happens to our body. We go to sleep and we are just not lying there. We are actually lying on the, on, literally on the operation theater. Or maybe if it is a car, then the car is lifted up and all the tune up is going on. That's exactly happened, so. Lining up our intestine gets repaired, our skin gets repaired, and then our brain, the trash is literally taken out. Everything has a clock. So for example, our hair also doesn't grow continuously. It grows only for few hours every night then it pause, sorry. Actually during daytime, it, uh, kind of for humans, it, uh, it's during daytime. So, you know, there are all these processes built in to repair, reset, and body every single day. Um, I, I can't get up early in the morning, even though, from what I can tell from your research, we, our bodies are designed to wake. With the morning sun and to start to get sleepy, you know, around like you said, nine or 10 after the sun has gone down. How do you explain that? Yeah means people can take a lot of chocolate but that can fit or you know, caffeine powder and then you put it into water. A lot of people do that, but supposedly you do this experiment and in fact somebody in Colorado did this experiment, Ken Wright a professor Ken write who is uh, professor there. He took his entire lab on camping trip. And these kids, you know, they are college kids and they strongly believe that they're night owl because they cannot go to bed before one o'clock in the morning. So they were very convinced that it's, it is their genes that are making them to stay awake till one o'clock. And when they went on camping, they realized that without all the stimulants, without the bright light of the city, then they were all falling asleep around nine or 10 at night. Then they said, well, let's come back again and do this experiment more carefully. So they even measured their nighttime melatonin rhythm and um, body temperature and all these very sophisticated measurement. what they found was when these kids are in college and they are studying on the bright light and have a lot of caffeine to keep them away, then they go to sleep after one o'clock at night. But when you withdraw all of these and then put them back to ancestral living in campsite, even if they're not hiking day long, you might argue that, oh, well they were tired, so that's why they fell asleep. No, it's not about that. Even their sleep hormone melatonin got reset and it began to rise, say six or seven in the evening so that after three or four hours they could fall asleep. So that was the kind of experiment that tell us that. Um, you know, if you ask people, almost half of the people on this planet will say either they're early bird or night owl. But if you go back and ask in very ancestral population or places where there is very little electricity, you don't see this 50% calling themselves night owl or night owl or earlybird. It may be one in 200 or one in 300. Who might have, so that raises another question. It may not be our clock is running differently, but some people may be more sensitive to light. Some people may be more sensitive to caffeine, so that even if they had just one cup of coffee in the morning, that would keep them awake till one o'clock at night. Whereas some other people may be much more resistant to caffeine or light. And irrespective of what happens, they will fall asleep at night, not 10 o'clock. So I think the, um, the take home message is it's may not be, our clock is running differently. It's our habit. and these habits, we don't know whether we are more sensitive to caffeine. Yeah means people can take a lot of chocolate but that can fit or you know, caffeine powder and then you put it into water. A lot of people do that, but supposedly you do this experiment and in fact somebody in Colorado did this experiment, Ken Wright a professor Ken write who is uh, professor there. He took his entire lab on camping trip. And these kids, you know, they are college kids and they strongly believe that they're night owl because they cannot go to bed before one o'clock in the morning. So they were very convinced that it's, it is their genes that are making them to stay awake till one o'clock. And when they went on camping, they realized that without all the stimulants, without the bright light of the city, then they were all falling asleep around nine or 10 at night. Then they said, well, let's come back again and do this experiment more carefully. So they even measured their nighttime melatonin rhythm and um, body temperature and all these very sophisticated measurement. what they found was when these kids are in college and they are studying on the bright light and have a lot of caffeine to keep them away, then they go to sleep after one o'clock at night. But when you withdraw all of these and then put them back to ancestral living in campsite, even if they're not hiking day long, you might argue that, oh, well they were tired, so that's why they fell asleep. No, it's not about that. Even their sleep hormone melatonin got reset and it began to rise, say six or seven in the evening so that after three or four hours they could fall asleep. So that was the kind of experiment that tell us that. Um, you know, if you ask people, almost half of the people on this planet will say either they're early bird or night owl. But if you go back and ask in very ancestral population or places where there is very little electricity, you don't see this 50% calling themselves night owl or night owl or earlybird. It may be one in 200 or one in 300. Who might have, so that raises another question. It may not be our clock is running differently, but some people may be more sensitive to light. Some people may be more sensitive to caffeine, so that even if they had just one cup of coffee in the morning, that would keep them awake till one o'clock at night. Whereas some other people may be much more resistant to caffeine or light. And irrespective of what happens, they will fall asleep at night, not 10 o'clock. So I think the, um, the take home message is it's may not be, our clock is running differently. It's our habit. and these habits, we don't know whether we are more sensitive to caffeine. Yeah means people can take a lot of chocolate but that can fit or you know, caffeine powder and then you put it into water. A lot of people do that, but supposedly you do this experiment and in fact somebody in Colorado did this experiment, Ken Wright a professor Ken write who is uh, professor there. He took his entire lab on camping trip. And these kids, you know, they are college kids and they strongly believe that they're night owl because they cannot go to bed before one o'clock in the morning. So they were very convinced that it's, it is their genes that are making them to stay awake till one o'clock. And when they went on camping, they realized that without all the stimulants, without the bright light of the city, then they were all falling asleep around nine or 10 at night. Then they said, well, let's come back again and do this experiment more carefully. So they even measured their nighttime melatonin rhythm and um, body temperature and all these very sophisticated measurement. what they found was when these kids are in college and they are studying on the bright light and have a lot of caffeine to keep them away, then they go to sleep after one o'clock at night. But when you withdraw all of these and then put them back to ancestral living in campsite, even if they're not hiking day long, you might argue that, oh, well they were tired, so that's why they fell asleep. No, it's not about that. Even their sleep hormone melatonin got reset and it began to rise, say six or seven in the evening so that after three or four hours they could fall asleep. So that was the kind of experiment that tell us that. Um, you know, if you ask people, almost half of the people on this planet will say either they're early bird or night owl. But if you go back and ask in very ancestral population or places where there is very little electricity, you don't see this 50% calling themselves night owl or night owl or earlybird. It may be one in 200 or one in 300. Who might have, so that raises another question. It may not be our clock is running differently, but some people may be more sensitive to light. Some people may be more sensitive to caffeine, so that even if they had just one cup of coffee in the morning, that would keep them awake till one o'clock at night. Whereas some other people may be much more resistant to caffeine or light. And irrespective of what happens, they will fall asleep at night, not 10 o'clock. So I think the, um, the take home message is it's may not be, our clock is running differently. It's our habit. and these habits, we don't know whether we are more sensitive to caffeine. We are less sensitive to caffeine. Or even recently, there is a new study that came out studying thousands of people over several weeks. That those who exercise in the late afternoon or early evening, they're likely to fall asleep later because likely, most likely that they have stress hormone that goes up. And when you exercise, your core body temperature also is going up. So that might, delay people falling sleepy. So these are, we have to think about all these habits. So the good thing is if we think about the habits. Then we can fix that. If you're, then you can fix that. But if you think it's in your gene, then unfortunately we cannot fix that. Some of them might have severe migraine pain. Some of them may have other conditions, um, with their mental health. So most normal people, when they call themself night owl or earlybird, most likely it's their habit. Yeah. So, uh, maybe I'll break it down to, uh, what elements in our habit affects what part of the clock. So, for example, we started this discussion with this, um, melanopsin or the blue light sensing protein. So this blue light sensing protein that's in our eye that, uh, senses blue light, but it also needs much brighter light. So that means during daytime, when we are outdoor, the daylight is the richest source of blue light because sunlight is strongly, has very strong blue light component, and even if you're not exposed to sunlight, even under a canopy, under a tree, even inside your car, even if it's a cloudy day, there is enough blue light. And during daytime, having exposure to that blue light does, um, various things. One is it resets our clock so that we are actually on the same circadian clock. So for example, those who do night shift, day shift, or they have traveled from east coast to west coast or one or two time zones, having exposure to that bright daylight actually helps to reset our clock. Second thing is the same light sensors actually connect to part of the brand that control our alertness or depression. So that means people who live in winter in Canada or northern countries, they know that in winter when they get less light, they get depressed. You don't have to live in Canada, actually. Yeah. So, uh, maybe I'll break it down to, uh, what elements in our habit affects what part of the clock. So, for example, we started this discussion with this, um, melanopsin or the blue light sensing protein. So this blue light sensing protein that's in our eye that, uh, senses blue light, but it also needs much brighter light. So that means during daytime, when we are outdoor, the daylight is the richest source of blue light because sunlight is strongly, has very strong blue light component, and even if you're not exposed to sunlight, even under a canopy, under a tree, even inside your car, even if it's a cloudy day, there is enough blue light. And during daytime, having exposure to that blue light does, um, various things. One is it resets our clock so that we are actually on the same circadian clock. So for example, those who do night shift, day shift, or they have traveled from east coast to west coast or one or two time zones, having exposure to that bright daylight actually helps to reset our clock. Second thing is the same light sensors actually connect to part of the brand that control our alertness or depression. So that means people who live in winter in Canada or northern countries, they know that in winter when they get less light, they get depressed. You don't have to live in Canada, actually. that's about light. now we can connect that, why this is important, and conversely, in the evening. If you have bright light, for example, if you walk into a, into a grocery store or a drug store, these days you have almost a thousand lux of light. So that means that light is a thousand times brighter than a candle. So that's the rough estimate. And at that light level, it'll put a break on your melatonin so you cannot fall asleep easily. means in the evening, we should avoid that light, and we should minimize our exposure to blue light. So that means you can have, you know, orange color kind of that light in your bedroom. so now we can connect what light is good for you during day, what light is good for you at evening or night. Then we can come to, um, food. So, although brain clock is very sensitive to light, we have clock in rest of our body, our digestive system, our heart kidney.

dr--supatra-tovar_3_07-30-2025_111119:

Yes. And if you don't, so many different types of difficulties can happen. If your eating window say is anywhere outside of that kind of time restricted zone, um, that's when you start to see, especially people eating late at night. Um. Are a lot more prone to metabolic disorders, uh, insulin resistance, things like that.

satchin_1_07-30-2025_111119:

right after we sleep, we have a spike of growth hormone and then our, then our testosterone and cortisol, they all reach their trough level and then they begin to rise. A lot of our hormones are kind of, you can say a rebalanced at nighttime. Mm-hmm. And our brain also takes out its own trust. So that means our brain cleanses itself during our sleep.

dr--supatra-tovar_3_07-30-2025_111119:

Yes, yes, absolutely. I think that, you know, I, and there's plenty of research to show that, um, you know, when, when he is talking about the trash being taken out, um, it's those kind of, uh, tangled proteins and plaques from the brain that can contribute to dementia and Alzheimer are actually washed away during sleep, so when we don't sleep enough, we can be much more prone to those kinds of neurological disorders.​

Head Shot

Dr. Supatra Tovar

Co-host