Transcription
What was Venice Beach before?
So imagine when the baby was born in the year 1900, she lived only after the years of 47. The major health challenges for infectious disease and microbes were the causes of disease. So scientists came up with antibiotics and vaccines to save life. And now, in the year 2017, when a baby is born, she is expected to live that long, healthy life of up to 80 years.
But as we grow old, almost all of us will suffer from at least one or more chronic disease. That's obesity, diabetes, cardiovascular disease, even cancer. And the scary thing is, the cure is rare. The medical cure works best only when it's combined with a healthy lifestyle.
But what is lifestyle? It's very confusing because it ranges from how many fruits and vegetables we eat in a day to taking 10,000 steps to be mindful. So we wanted to fit all of these into a very simple and crisp definition. And we came up with this: lifestyle is what, when, and how much we eat, sleep, and move on a daily basis.
Almost all of you know what we eat affects our health. And how much we eat also makes us healthier or sick. What about when? We're not talking about eating breakfast. We're talking about a different time. And why the timing matters?
The reason timing matters is all of our bodies have a timing system or a clock that runs on a 24-hour basis. It's called the circadian clock or CKD and rhythm. For example, if you locked me inside this room with no access to any timing, then I will go to sleep around 10:00 p.m. at night. And my deepest sleep will happen around 2:00. And anticipating morning, my body will start to warm up. And as soon as I wake up, my melatonin level will drop and stress hormone level will rise. So around noon, my brain will be at its peak performance time. And around afternoon, my muscle will be at its peak performance time. And as the evening sets in, my body will cool down and melatonin level will rise. And again, I'll go back to sleep around 10:00 p.m. It will go on and on every 24 hours.
So overall, this biological clock or circadian rhythm organizes our life into sleep, nutrition, and physical activity to the right time of the day. These three fundamental pillars of our health have to happen at the right time. And if we stay awake late into the night, finishing an assignment or taking care of loved ones, the next day we feel horrible. And if we continue to do this, then our clocks break down and we get a host of different diseases. And this is just a small, simple set of those diseases. They range from ADHD, asthma, diabetes, obesity, depression, anxiety, and even after cancer. So this tells us how important this circadian clock is.
But how does the system work? So for the past 20 years, what we have discovered is every morning, as we open our eyes, the bright light signals the retina and synchronizes a small part of the brain that has the master circadian clock to the day/night cycle. And this brain clock sends hormonal signals to the rest of our body.
But what is really surprising is this: just like our brain has a clock, almost every organ in our body, even every cell in our body, has its own clock. And the brain signal synchronizes all these clocks so they work together to produce daily rhythms in behavior, physiology, and metabolism.
And when we move from one time zone to another time zone, or when the long summer days transition into short winter nights or winter days, then what happens is the change in daylight is sensed by our eye. And then our clock resets to the new daylight. But a very surprising thing that kind of confused scientists for almost 100 years was this: even blind people, when they move from one time zone to another time zone, they could reset their clock perfectly fine, as if there was a hidden light sensor in the eye we didn't know about.
So almost 15 years ago, we made a huge discovery that made it to the top 10 breakthroughs of the year by the prestigious Science magazine. And the discovery was: we found the blue light sensing protein called melanopsin that's present in 5,000 squiggly neurons in our eye. And the same protein is found in both normal people and also blind people. And these neurons are literally hardwired to the master clock in our brain.
But these neurons actually work slightly differently. In a moonlight night, you may be able to see moonlight or you can see candlelight. But that light is not enough to fully activate melanopsin. So the brain thinks it's dark. So our body's natural sleep hormone melatonin rises at night, and we get good night's sleep. And next day, when you wake up and go outside for an hour in the bright light, that bright daylight fully activates melanopsin. It resynchronizes our clock to the day/night cycle. It improves our mood. We feel less sleepy and it reduces depression.
But over the last hundred years, we have moved into indoor spaces. We spend more than 90% of our time indoors. The bright light and bright screen at night activate melanopsin. It reduces sleep hormone melatonin, and we have sleep disruption. And the next day, when you wake up to an alarm clock and stay most of the day indoors, it further confuses our clock because our body doesn't get enough light to resynchronize our clock. And if it continues, then we get depression and anxiety. And that's why light for vision is not the same as light for health.
This is a very simple idea 15 years ago, but that has started a new revolution in lighting. In fact, now architects and lighting engineers are coming up with new security and lighting for buildings of the future. And right now, almost every smartphone and every laptop produced comes with an automatic program to change the screen brightness and screen color at night. So it's really humbling to see a very simple discovery we made 15 years ago. The fruits of those discoveries have already reached billions of people, and there is knowledge in their hand to improve their circadian rhythm.
But we did not stop there. We knew that people who sleep less or sleep late become sick. So we wanted to know what happens when people don't sleep enough. So when we peer into lighted cities or lighted buildings or into lighted living rooms of people, then people don't just stare at lighted screens at night. As long as they stay awake, they eat. So that means as long as their eyes are open, our mouth is open. So we wanted to know what is the effect of food on our circadian clock.
So we went back to the lab and we made another huge discovery. That is, just like light at night distorts our brain clock and keeps us awake for the wrong time, food can disrupt circadian rhythm and disrupt our normal metabolism. But how do we figure that out?
So just imagine, suppose say in the morning, you have your first breakfast. As soon as we have that first meal, the body starts to use carbohydrates as energy and stores a little bit of fat. And as we continue the day with lunch and dinner, our body continues burning carbs and storing fat. And in the evening, after the last meal, as we continue into the night, then the body runs low on carbs and starts to burn some fat. So every day, if this rhythm continues, then we have this complementary or opposite rhythm in burning sugar and burning fat. And these two rhythms actually help us maintain body weight.
But what happens if we just extend that last meal late into the night? So in this case, our body's circadian rhythm becomes much slower. So it continues to make fat for a very long period of time, and there is not enough time actually to burn fat naturally. So imagine if we compare the same person eating everything within 10 hours, we'll have a very robust circadian rhythm in metabolism and we'll have few hours of burning fat. And the same person spreading the calories over 15 hours may not reap that benefit.
Was it a wild thought, or is there some truth to it? So we went back to the lab and then we brought two identical sets of mice, the same born to the same parents in the same room. Now, we gave one group of mice a fatty food, and they could eat whenever they wanted. And the second group was trained to eat the same identical diet in the same number of calories every day. And we weighed the mice and weighed the food every week to make sure that these two groups ate the same number of calories. And we did this for 18 weeks.
And at the 18 weeks, there was something really surprising. The mice that ate this very random time were obese. They could not burn enough fat. And mice that had the same number of calories from the same fatty food were 28% lighter. And the reduction in body weight was largely due to reduction in body fat. And this was really a Eureka moment because for 400 years, nutrition science has taught us to count calories and watch carbs, protein, and fat in our diet. And what we discovered is it's not only what you eat, when you eat also matters.
So we went back to the lab again and then made sure that what we're discovering is true and applies to a lot of different diets. So we brought mice and gave them food for 8 hours, 9 hours, 10, 11, or 12 hours. Sometimes we even gave the mice week-old partying. And then sometimes we gave them food that is high carb, high fat, high sucrose, even high cholesterol. And when we go back and compare these two groups of mice, the result came out always the same. Mice, when they eat all their food within 8 to 12 hours, remain healthy irrespective of what food they eat. Whereas mice that ate at random times, they become fat.
And there are two surprising things that also came out. One is, if we take fat mice and give them food within 8 to 10 hours, then they become normal and all their sickness goes away. And if we take healthy mice eating healthy food, but randomly throughout 24 hours, then over the period of time, they also become sick. This was really eye-opening.
And what all of these mouse experiments told us was, just like our brain has a clock to make us sleep and wake up every day, all our organ clocks need some downtime to rest, reset, and rejuvenate every day.
So we wanted to test when do people actually eat and can they change this behavior? So we started a study. And that's actually all online. And with an app, people can go to this website, mycircadianclock.org, sign off, and then download an app. And people love taking pictures of everything. So we asked them to take pictures of everything that they eat and drink over a two to three weeks period. And when these pictures come to our server, we organize them on a time scale so that it's easy for us to see how their eating pattern is.
So as we line up this timing of their food along a time scale, we also see something very interesting. That is, most people, at least this particular example, it's very random. And you all can actually sign up. This study is open to all of you, and you can download the app and you can see your own photograph. And what is interesting is if we look at this person's eating pattern during weekday and weekend, they all look random. And if we combine the data to weekday or weekend, then what we find is, although this person did not travel, it almost looks like he ate in one time zone during weekdays and went to another time zone on weekends. And if we combine this and plot it around a clock so that it's easy for you to figure out how this was an 8-hour eating window over 24 hours, then what you'll find is this person could eat any time of the 24 hours.
You might say that this is all random, one outlier. But actually, almost all 150 people in our study who had a regular nine-to-five job and claimed that they eat healthy, had similar eating patterns. The bottom line is, 50% of adults eat for 15 hours or longer. So that means if your first sip of coffee is at 6 o'clock in the morning, your last sip of wine or last bite might be at 9:00 or later at night.
So with this knowledge, we asked a very simple thing: if we take overweight people who eat for 15 hours or longer and ask them to choose their own 10 hours that fit their lifestyle and eat everything that they want within that 10 hours, what happens? So in the first group of people, we brought some people who are overweight and they were eating for 15 hours. We asked them to choose their 10 hours. They did that for 16 weeks. And after 16 weeks, they were lighter. And then we let them go free. After one year, we brought them back to the lab. Surprisingly, they still maintained that lost body weight. And when we asked them why did you stick to this habit? It was not the body weight loss that they were excited about. They said they could sleep better, they felt more energetic throughout the day, their joint pain reduced, so they could go for a walk or run. And this was really exciting.
And in the next phase, over the last one year, thousands of people from all over the world are signing up for our study, and they are sharing their data and their sharing of their experience with what happens when they use their timing of eating and we've become more disciplined and eat for 10 to 12 hours. And all of these are teaching us one big thing. That is, our body's biological clock is just like a simple scheduling program. It has programmed us to eat and sleep at the right time of the day or night. And if we stick to this, our appointment with our biological clock, then we stay healthy. And just like showing up randomly at work can ruin your career, showing up for lunch, breakfast, and dinner, or for your sleep at random times of the day can ruin your health.
But the good news is, this is all reversible. Even if we have some chronic condition, if we select our 10 to 12 hours eating period and sleep well, we can reverse or cure a lot of chronic diseases that affect more than a billion people on this planet. Thank you.