DR. SATCHIN PANDA is a leading expert in the field of circadian rhythm research. He is Associate Professor in the Regulatory Lab at the Salk Institute, a Pew Scholar, and a recipient of the Dana Foundation Award in Brain and Immune System Imaging. His book, The Circadian Code, has helped many people to regain energy, sleep well and lose weight. In part 2 of his discussion with UDAY KUMAR, he speaks about how he developed his ideas, and what inspired his research.
The Biology of Time – Part 2
Q: Regarding the point you mentioned about sleep and sleep discipline, I have an Android phone and although I never knew anything about the blue light filter somehow I would turn it on and it would feel softer on my eyes. Then I came across your research. What triggered this whole curiosity and life changing discovery?
DP: For a very long time, animals and humans have reset their brain clocks in response to light. Then there are many blind people who cannot see, cannot even see the headline of the New York Times, but when they travel from one place to another place, they can readjust their clock to the new time zone, just like normal people. But then there are other types of blind people who have lost both their eyes because of surgery or an accident, and they cannot reset their clock. That means there must be a light sensor in the eye, which is not for seeing, but may be essential for sensing.
So, that clue was there for almost 50 years, and everybody was trying to figure out where this light sensor is. Then, after the human genome project, it became easier to look for it because we had the information. That’s how we stumbled on the melanopsin photoreceptor. If you remove the melanopsin gene in a mouse, it cannot sense light accurately, and cannot reset its clock. It takes a very long time to reset at scale.
Then we figured out that it’s a blue light sensing protein – it senses blue light. That makes sense because during the daytime we have a lot of blue light in sunlight. So, we are designed to sense that blue light and become a lot more alert during the day. At night-time we don’t need blue light because it keeps us alert. Candlelight and firelight don’t have too much blue light. So, we are designed to see more blue light in the daytime and less blue light at night.
Unfortunately, nowadays, what has happened is that opticians want us to have a blue light coating, which is actually not the right thing to do. You need blue light during the daytime, whereas you don’t need blue light at night. So, it’s better to have two pairs of glasses. If you don’t get enough blue light during the daytime, you can become depressed. Cell phone tracking data show that we spend more than 87% of our time indoors, and most of our indoor lighting is not good. In my living room, I might have 250 to 300 lux of light, whereas on a cloudy day in New Jersey, outside there will be 10,000 lux. Right now, where you’re sitting, since you’re away from your window, you may be sitting in 200 lux. Out of that, blue light is a small fraction. If you filter out the blue light, then of course you may not get so much eye strain from looking at the screen, but you will not get the upliftment that you get from going outside.
The second aspect is that most opticians are selling blue light filtering glasses. But is it filtering enough that is biologically significant? The answer is no. Most blue light blocking glasses that people are buying filter out maybe 5 to 10%. It is like you’re standing outside, and you feel it’s too much sun, and you get a transparent umbrella and hold it. So, in most cases it’s 5%. The glasses that really filter out blue light will look orange. Only orange and other spectra will go through, since blue is filtered out, so we see them as orange or even red. The real blue light filtering glasses are orange, yellow or red.
Some people who get migraines will benefit from filtering out blue light when they go out, but they’ll also benefit just from wearing sunglasses, because that will filter out a lot of light, including daylight. At night-time, for people who cannot sleep easily, and cannot control the lighting, the real blue light filtering glasses do help. For example, somebody working in a grocery store, whose shift ends at 10 p.m. or midnight, who comes home completely jazzed up because of the light and cannot asleep, will benefit if they wear the blue light filter glasses for one or two hours before the shift ends. That will help. So, there are specific cases where they’re more effective, while there are many cases where people are just paying for nothing because there is no benefit that is significant.
Q: Here are my $20 glasses from Amazon! [chuckles]
DP: Maybe you’ll get some placebo effect.
Q: Exactly! It’s placebo and now I totally know it!
DP: Just look at the glasses, do they actually look slightly yellow or orange? If so, then you know.
Q: I think a lot of families will find this advice helpful because, with homeschooling, designing an ergonomic workspace for kids has become more important than for grownups. There’s just so much that they have to do with this new change.
The other aspect of your research, which I have started implementing, is time restricted eating. Is it the same as intermittent fasting, or is it different? I like time restricted eating better.
DP: In the scientific literature, intermittent fasting is a broad term, because it just means doing something intermittently. It goes back to the research on calorie restriction: When caloric intake in mice is reduced by 20 to 40% then the mice live longer. That led to the idea that we should restrict calories, but then it is not easy to restrict calories every day, so they came up with the idea that we should eat every other day: There is a diet called the “Every Other Day Diet.” And then it was discovered that people who didn’t eat for two days out of seven might get similar benefits, and that people who eat less than 1000 kilocalories for five days in a row every two months also get some benefit.
Some people who get migraines will benefit from
filtering out blue light when they
go out, but they’ll also benefit just
from wearing sunglasses, because that will
filter out a lot of light, including daylight.
So, all of these are intermittent not continuous. That’s why they lump them together as intermittent fasting. But the word “fasting” repels people who would benefit, like people who have diabetes. They are told by their physicians that they should not fast, because they may become hypoglycemic. In our clinical study, we tell them that they can simply choose their 10 hours, and they can eat whatever they’re currently eating, then they say, “Yes we can do it.” If we tell them that “You have to fast for 14 or 16 hours,” then psychologically it becomes difficult.
Q: Again, the positive reinforcement that you spoke about earlier: What is the message that helps a person take a positive step forward? I love the idea of time restricted eating. What you also showed is that it’s not about how much or what, but it’s the time you eat, the discipline, that makes a lot of difference.
It was a Japanese scientist who received the Nobel Prize for autophagy and there was a lot of conversation about the positive benefits of fasting and how it helps with autophagy. So, in the Indian context, there is the idea of Ekadashi. I think our ancients knew the benefits of fasting.
DP: In the Indian culture there is weekly fasting, which is similar to intermittent fasting. Two days in a week you fast, and that gives similar benefits. Reducing calories for several hours over a couple of days does give a lot of benefit.
Q: Is there any research on the benefits of fasting on emotional stability? I was reading some yogic literature where a person who was irritable was told by his teacher to eat less in the evenings, that it would help him. So, I’m just wondering if scientific research also shows any correlation between emotional poise and restricted eating.
DP: Yes, we anecdotally hear that people who have anxiety benefit from this and can avoid a panic attack. And I think in the book I describe how there is a hormone that is passively broken down in the gut that causes panic attacks. So when that hormone is managed, it may no longer cause anxiety.
But what is interesting is the history of fasting, I don’t remember where I saw it, perhaps in a documentary, where Dr. Valter Longo talks about fasting. Another interesting thing was done by Russian scientists who were doing some experiments to try to figure out how to improve the health of institutionalized patients with depression and bipolar syndrome. There was a very difficult patient who was bipolar, and one day he said, “I’m not going to eat.” The warden gave up and said, “Okay, if you’re not going to eat, don’t eat. I’m not going to force feed you.” They used to force feed the patients, but instead he decided, “Okay, until he begs for food, we’re not giving it.” So, the patient went without food and just had water for six days or even longer.
After that, he came back completely cured and said, “Well, I feel much better! I’m ready to leave as I’m completely normal.” The physician warden, who was a little curious, wondered, “Was it the fasting or did something else happen?” So he tried this experiment on many other patients with emotional problems, and found that fasting actually helped a lot of them, not all. So, in Russia, a lot of the experiments on fasting and health started from emotional health.
When we fast, the brain and the rest of our
nervous system go through changes because
they’re exposed to ketones as an energy source.
For mice with certain neurological diseases, like
Huntington’s Disease, time restricted eating helps
them to sleep better, and their activities are much
better. At the same time, for depression and other
conditions, bright daylight is still the best
antidepressant and it’s plentiful and free.
When we fast, the brain and the rest of our nervous system go through changes because they’re exposed to ketones as an energy source. For mice with certain neurological diseases, like Huntington’s Disease, time restricted eating helps them to sleep better, and their activities are much better. At the same time, for depression and other conditions, bright daylight is still the best antidepressant and it’s plentiful and free. A lot of people don’t go outside enough. Because I wear my light sensing watch I see how much light I am exposed to, and if I don’t make an effort, even in San Diego, California, I don’t get as much as I should. If you think about it, most of the time we are indoors, we have curtains or blinds on the windows, and we are not always sitting next to a window. Then, as soon as we go out of the house, we put on sunglasses and get into the car.
So, we are never actually exposed to much daylight. Daylight is very useful in reducing depression and people in Nordic countries know this, so they even pay to sit in a brightly lit room, with 10,000 lux of light, as an antidepressant. At Geneva airport, also, there are light rooms where you can pay to sit.
The foundations of day-to-day
physical health are also three
factors: sleep, nutrition, and
Q: I remember when I first came to the USA, I was in Virginia in the winter. Inside the house, with incandescent light, I would feel almost claustrophobic by evening. I had to step out, take a walk, and sit in the sun. It took me a good two to three years to acclimatize myself to the change in lighting. When we bought our current house we added extra windows. I didn’t realize it when I had it, but when I didn’t have it I knew immediately.
Any parting words that you want to share with our readers, especially during Covid times?
DP: Sanitation and social distancing will help prevent the virus from getting into our bodies, but to improve resilience we need a good circadian rhythm. Then, even if we get the virus we may not become too sick. For example, among NFL and NBA team players, there is no death for those who tested positive. All these elite athletes have a very strict regimen – how much sleep they get, their exercise regime, and they’re always outside practicing. That’s a clear example of a cohort of nearly 1000 people who had the same rate of infection as the general public, but no one went to hospital.
Paying attention to sleep activity, nutrition, and being outside builds up resilience, so that even if you test positive you may not die.
This is a direct effect, and there’s also another indirect effect. People with diabetes, heart disease, and high blood pressure often have a more severe form of Covid, but we also know that time restricted eating can help reduce the severity of these chronic diseases, so indirectly a circadian lifestyle will also reduce the risk of suffering from the virus.
Q: Sir, thank you so much for all the great work you are doing.
DP: Thank you. Have a nice day.
Q: You too! Bye.
Interview by UDAY KUMAR
Dr. Panda is a leading expert in the field of circadian rhythm research. He is Associate Professor at the Regulatory Lab at the Salk Institute, a Pew Scholar, and a recipient of the Dana Foundation Award in Brain and Immune System Imaging. His book, The Circadian Code: Lose Weight, Supercharge You Energy, and Transform Your... Read more