And what is interesting is, this is particularly important for children because their brain is still developing. And when children go through early childhood circadian disruption, they are more prone to diseases like ADHD and autism. So this new simple idea, that we need more bright blue light during the daytime and less light, or darkness, at nighttime, is starting a new lighting revolution. And you are just getting a glimpse of this new light revolution when your smart screen and computer screen dim down and turn orange at nighttime. But there is more to it.
Just think about it: Circadian lighting at daycare and schools will promote healthy brain development and promote learning. Circadian lighting at home, factories, offices, will promote alertness and improve productivity. Circadian lighting at hospitals or retirement homes will promote health and accelerate healing. And in fact, right now, there is new circadian lighting in our International Space Station to promote productivity of our astronauts and make them have better nights’ sleep. So light is not the only factor that affects our clock.
In fact, just like light in the middle of the night disturbs the brain clock and breaks the chemical balance in our brain, food at the wrong time can disturb the peripheral clock and break the metabolic balance in our body, and that will push us towards disease.
Now, let’s figure out how. So in the morning, our stomach is actually ready with the right amount of hormones and digestive enzymes, and even good gut microbiome to digest food. So after we eat our first breakfast, a body absorbs enough carbohydrates and uses it to fuel our body. At the same time, it saves a little bit of nutrient as fat.
As we continue at lunch and dinner, the same process continues. And after the last dinner, last bite, a body slowly goes low on carb. At the same time, the circadian clock cranks up morning fat. And after a few hours, the clock turns into a reset and repair rejuvenation mode. That means that it turns on enzymes that will break down cholesterol and toxins.
It also turns on mechanisms to repair the DNA that we have damaged during the daytime. And a lot of cells that are damaged on our stomach lining or our skin lining are also replaced with healthy new cells so that allergy-causing chemicals or bacteria cannot get into our body. So after 12 to 16 hours of fasting, when we eat our next breakfast, the cycle of nurture, rejuvenation continues. But imagine if we delay that last bite late into the night. So in this case, this daily rhythm in metabolism becomes shallow.
There is not enough time to burn fat, and there is not enough time to break down the toxins, cholesterol, etc. So, you can imagine that somebody who eats within ten hours might have a much better circadian rhythm, whereas somebody who eats within 15 hours may not. To test this idea, we went back to the old lab and brought two identical groups of mice born to the same parents, raised in the same room, same age. And one group of mice got the standard Western diet to eat whenever they wanted. And then the second group was trained to eat the same number of calories from the same food, but they had to eat everything within eight to 12 hours at nighttime when they’re supposed to eat.
And we measured the food and weighed the mice carefully every week for almost 18 weeks. At the end of 18 weeks, the first group of mice, who ate randomly, were obese, where at the same time, they had a host of different diseases – they were really morbidly sick – where the second group that ate within eight to 12 hours were completely healthy. But what is more surprising is this: If we take those morbidly sick mice and give them the same diet, same number of calories, and they have to eat only within eight to ten hours, they become healthy. This was a really earth-shattering, eureka moment for us, because for the first time in the history of nutrition science, we found that when we eat is as important as what or how much we eat.
Well then, how do we translate that to humans? The first thing we wanted to know is, when do people eat? To do that, we started a new study – and people usually sign up for the study at mycircadianclock.org – and then, since people love to take pictures, we asked them to take pictures of every single thing that they eat or drink, and we’d do the rest. So when the pictures come to our server, we add them on a timeline so that it’s easy for us to figure out when they eat. And they continue taking pictures for almost two to three weeks. So that we can take a nice snapshot of their food life during the weekdays and weekends. And you can see, for this particular person, he or she eats very randomly throughout the day.
And if you look at the weekday and weekend pattern, those are also very random. And if you combine the weekday and weekend, there is another interesting thing that comes up. It appears as if the person is on the East coast during the weekday and comes to the West coast on the weekend, which is also very bad for our circadian clock. Now, if we combine all of this data and plot it as if we are looking at a clock, then you can see that this person was eating almost around the clock. He’s not an outlier, actually.
If we look at the first 150 people who had signed up, nearly 50 percent of adults who actually have regular 8 to 5 jobs, eat for 15 hours or longer. So that means if they have their first bite at 7:00 in the morning, the last bite or last sip of wine happens at 9:00 or later. What is interesting is, if we feed mice even a healthy diet, and they eat for 15 hours or longer, then slowly they become overweight and they get all these diseases. So that’s why we wanted to ask a very simple question. We brought back people who were eating for 15 hours and were a little overweight, and asked them to eat whatever they want within ten hours of their own choosing, and we wanted to see what happens to them.