Dhru Purohit Show
Supercharge Your Sleep and Improve Your Longevity Using the Power of Intermittent Fasting & Circadian Biology (Rebroadcast)
Wed, 05 Mar 2025
This episode is brought to you by Bon Charge and Momentous. We used to think circadian rhythm only applied to sleep. But emerging science has revealed a link between our circadian rhythm and metabolism, cognition, risk for chronic diseases, and many other crucial aspects of our health. Our biology was designed to live in sync with a natural light-dark cycle, but modern-day society has disrupted this natural balance. Today on The Dhru Purohit Show, we’re revisiting one of our favorite episodes with Dr. Satchin Panda. Dr. Panda dives deep into his groundbreaking circadian biology research and shares how leveraging your circadian rhythm can dramatically improve your sleep, lower your risk of chronic disease, and improve your cognitive function. They also discuss how time-restricted eating, exercise, and light can be used to help program your circadian rhythm and why it’s especially important for shift workers to take advantage of these tools. Dr. Panda is pioneering circadian biology research. He is a professor at the Salk Institute for Biological Studies, a Pew Biomedical Scholar, founder of the UC San Diego Center for Circadian Biology, and recipient of the Julie Martin Mid-Career Award in Aging Research. Dr. Panda has spoken at conferences around the world about his work on circadian rhythms and diabetes, including Diabetes UK, the American Diabetes Association, the Danish Diabetes Association, and the professional diabetes societies of Europe and Australia. In this episode, Dhru and Dr. Panda dive into: Why late-night eating is so detrimental to our health (2:15) Organ systems that have a circadian rhythm (8:24) Common ailments that could be related to circadian rhythm disturbances (14:11) Night-shift work and cancer risk (20:19) How poor sleep perpetuates bad food choices (27:00) What happens in the body when you rely on an alarm clock (44:01) Why you need to accumulate sleep debt for better sleep (51:25) Time-restricted eating and sleep (1:00:40) How to combat fragmented sleep (1:15:35) The best time to work out (1:55:50) The link between exercise and cancer (2:07:55) Positive changes for better sleep health on a global scale (2:17:20) Strategies for night-shift workers to combat circadian rhythm disruption 02:45:10) Dr. Panda’s research in firefighters (2:48:46) Tips for optimizing your circadian rhythm (3:14:20) Where to follow and support Dr. Panda's work (3:27:50) Also mentioned in this episode: The Circadian Code: Lose Weight, Supercharge Your Energy, and Transform Your Health from Morning to Midnight The Circadian Diabetes Code: Discover the Right Time to Eat, Sleep, and Exercise to Prevent and Reverse Prediabetes and Diabetes Download the MyCircadianClock app Try This: 6 Crazy Facts About Sleep Try This: How Exercise Helps Fight Cancer For more on Dr. Satchin Panda, follow him on Twitter @SatchinPanda, Instagram @satchin.panda, or his Website. This episode is brought to you by Bon Charge and Momentous. Right now, BON CHARGE is offering my community 15% off; just go to boncharge.com/DHRU and use coupon code DHRU to save 15%. Optimize your energy and mental clarity with the Momentous Three: Protein, Omega-3s, and Creatine made by and used by the best. Go to livemomentous.com and enter promo code DHRU to get 20% off any order. Learn more about your ad choices. Visit megaphone.fm/adchoices
Chapter 1: Why is the timing of eating important?
Dr. Sachin Panda, welcome to the podcast. Pleasure to have you here. I wanna 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, then what we eat.
Circadian rhythm essentially relates to almost a daily timetable of things that has to happen in our body, whether it is 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 do I 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-hour 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 the 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 the three big principles that are coming into play.
And you mentioned 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 for 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 us kind of a nice toolbox for each one of us to adopt.
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Chapter 2: What are the organ systems with their own circadian rhythms?
Absolutely. So what I'm hearing you say is big picture, the most important thing to understand, and it has all sorts of applications, including when to eat, when to sleep, when to be active, when to potentially take a drug, as you mentioned. People are on pharmaceutical interventions, so it's most efficacious and effective for the body.
But first, we need to understand that not just our entire body has a circadian rhythm, which I think most people who are listening today know, but different organ systems also have their own biological clock. Give us an understanding a little bit, for example, of... an organ system or cells inside of the body that have their own individual rhythm that many people may not necessarily know about.
Yeah. So let's start with what we do every day. Eat. So when we eat, our digestive system digests the food, absorbs the nutrients, sensitive blood, and then... Our pancreas does its duty to control blood glucose. So now if we start with the digestion process itself, the first stage of digestion is that happens in our mouth.
As we salivate, there are many enzymes in our saliva that breaks down some of the food components. And there is a circadian rhythm to this whole process of salivating. And we are more likely to produce a lot of saliva during our wakeful hours or during the daytime. And the saliva production actually goes down, way down, right around when you go to bed.
And I'll get to that point why this plays a role. So now the next step is digestion and that happens in the stomach and a lot of the enzymes that break down food that are produced in what we call the pancreas, it has two different roles. We always hear about the insulin production part, but pancreas also produces a lot of stuff to digest our food. And then what we now know is that
That process producing acid to break down food and these enzymes to break down the food, all those are also circadian. So that means during the daytime there is 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 stick or something thinking that somebody is in bedding. 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 our esophagus 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 others. Right. So now in the next step in digestion is after the stomach is digesting food, it goes to the intestine and the intestine kind of has a peristaltic motion.
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Chapter 3: How does late-night eating affect health?
And although we are not growing after reaching 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 nighttime. 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 live in 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 see that people are struggling with in 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 right yeah is there anything else that you'd want to mention
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Chapter 4: What can shift workers do to maintain their circadian rhythm?
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 palatable, salty, sugary types things. They want chips, which again- are types of foods that, again, that are not the ketogenic route.
They contain a lot of starches. Starches are broken down as sugars inside your body. And not only are you inhibiting your melatonin production, which is going to throw off your sleep, you're also keeping your blood glucose around higher longer, which has all sorts of downstream effects.
Yeah. And also since it's the time when insulin production, it's not that insulin production has shut down. It's actually there is a trickle of insulin that comes out and it continues for a 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. 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? Could. contributing to weight gain.
Yeah. So this is something that has to come from clinical studies, but 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, hyperpalatable foods the next day in addition to just feeling not 100%.
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Chapter 5: How does sleep debt accumulate?
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? Yeah, I've heard you talk about this.
Please break it down.
Yeah. It's not that somebody has to have a job like in police department or 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 our body is actually not checking whether you checked into 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 5 a.m.? 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 being engaged in some kind of work. Engaged in some sort of work. Some sort of work. You're not just lying in bed with 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 concerned.
Because your body is not resting. And if you do that, on an average, once or twice a week, that is shift work. Because your habitual sleep time, suppose, is 11 o'clock every night. And once or twice, you are staying awake either till 1 o'clock in the morning. Or you're 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% of us are shift worker or we are living the life of a shift worker. So if you look at the average person who's listening a day.
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Chapter 6: What is the link between exercise and sleep?
And these are the studies that are mostly done by initial, like a little bit of contribution from private philanthropies, private philanthropy. And when you think about private philanthropy, we always think of Bill Gates and, you know, we're putting billions of dollars into it.
We think of the mega millionaires, billionaires who are funding things.
Yeah. But actually, some of the studies are done with small contributions from people. So that's why, just think about it. If a million people just donate their one cup of coffee worth of money to a lab, we're talking about two to three million dollars. Absolutely. Just a million people, one coffee cup. Right.
And that will do a huge amount of research because a typical large federal grant is about that size. And there's also a reason why we should not play with honest taxpayers or federal money on random ideas, because sometimes these ideas are very out of the box. They're bold ideas.
They may not work, but if they do, they can have big implications.
Yeah. So that's why the research enterprise also works in a very systematic way. First, we try to do small studies in, say, animals. And whereas where we work with, say, fruit flies or a little bit of cells in a disc. And then we play with that idea to see whether it actually has some benefit.
Also, whether it has some risk, because sometimes some ideas can actually kill fruit flies, and it's okay. But we should not play with that idea on humans. So we produce that initial idea testing, and for that we need this philanthropy money, private donations, because this is where we... I personally don't want to use... honest taxpayers' money.
When we think about federal money, we are thinking about, okay, some federal government writing a check. No, actually that money comes from people who are- Taxpayers.
Taxpayers. And it's great that we have the NIH and we have that, but often the funding that can come from there might be at the end stage of research that people are working on that it's the last little bit. For some of these bolder ideas, it could be a little bit tougher to get funding. Yeah. But that's actually what a lot of people and I know that's what I'm interested in on this podcast.
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Chapter 7: How can light exposure improve sleep quality?
But I'd love to have somebody like Dr. Rhonda Patrick or Andrew Huberman or other individuals saying, Hey, look, pay attention to these, you know, few things. I know Tim Ferriss has done that a little bit.
Yeah, yeah, yeah.
psilocybin research and plant medicine that's there. Something like that would be amazing. People could feel like they could participate. But in the meantime, if you look around, even labs like your own, you guys do accept donations?
Yeah, we do. Actually, we'll have the link to our labs donation phase. And this is where even small donations actually help because sometimes the trainees, the PhD students and then postdocs who have finished their PhDs who could have gone to make big bucks in pharma or in other places. They're actually passionate about research.
They're working and then sometimes they want to go to a conference to present their results. Sometimes they want to just have subscription to a journal that's only a few hundred dollars. So these are really some of the key contributions.
As I said, a long time ago when we started this time-restricted feeding or time-restricted eating, which is now famous as intermittent fasting, that was all funded by small philanthropic grants. And if we think about, okay, what is the return on investment on those philanthropic grants? It's 100 times, 200 times.
Yeah, because now this idea of time-restricted eating is out there in the zeitgeist. And I know many, many people who feel like they've improved their body composition, lost weight, feel better, sleep better because they've been able to practice that, but the research had to be shown for the newspapers and everything else to pick it up, for book deals to happen, et cetera.
So, I mean, it's an incredible return on investment for the lab that you, for the people that have helped fund that research. Yeah, so let's get back to- Yeah, let's get back to that. But that was a good little tangent. I'm gonna be the first to donate after this podcast is done. I wanna come back to sleep for a second.
You've shared something very important, which is, you're not against alarm clocks, but you just want people to understand what happens when you consistently have to wake up from an alarm clock, right? So what's happening to the body when you're reliant on waking up from an alarm clock And could there be a different way of going about things? So I'd love for you to chime in about that.
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Chapter 8: What strategies can be used to optimize sleep?
Yeah. And particularly, you know, when you're talking about sleep, we're always thinking about metabolic health and age. But we should start that practice when, you know, our kids are going to middle school and high school, because that's the time when disruption, sleep disruption begins at that stage. Because that's the time when we put a lot of pressure on our kids.
And also the kids are also feeling pressured by their peer to stay up late into the night and and they lose sleep. And when they lose sleep, then that increases the risk for anxiety, depression, bipolar, and all these brain health issues that we are witnessing.
And this has become a pandemic because, you know, some of the surveys that you see, we see that one in five high school students are so depressed that they thought about suicide. Those kind of numbers are what fraction of college students are actually seeking mental health
But we don't talk about how to structure high school, college, and then in a way that kids can actually get sleep that they really deserve. Means if we want to invest in kids' future, One investment, one thing that we can do is let them sleep for at least seven hours.
If we think about, if we look at high school students, 90 plus percent of high school students do not get the amount of sleep the body needs. The same thing applies to college students. And when they don't sleep, They can counter it with, so one thing is there is mental health issues and sometimes there is also substance abuse issues that come from reduced sleep.
So we have to think about the whole spectrum from high school kids, all the middle school kids, all the way to older adults. You mentioned sleep debt.
Yeah. 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 a 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 students, 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.
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