BITESIZE | The Science of Sunlight: How 20 Minutes a Day Could Transform Your Mood, Energy & Sleep | Dr Roger Seheult #684

Rangan Chatterjee (0:01)

Welcome to Feel Better, Live More, Bitesize, your weekly dose of inspiration, insights, and practical ideas to help you live well and thrive. Today's Bitesize is from episode 586 of the podcast with quadruple board certified physician, Dr Roger Seheult.

Now, most of us know that getting outside is good for us, but we may not realize just how powerful natural light can be for our health. In this Bitesize, Roger explains some of the science of sunlight and shares why spending time outside can play a vital role in how we sleep, how we feel, and even how ourselves create energy.

If we think about light and the fact that we're living these indoor lives now, and yes, for many years, we've just thought sunlight equals vitamin D. Wait a minute. Sunlight equals many things. One thing is vitamin D, but there's many other things that sunlight does on our body as well. So we might be missing one of the most important ingredients for health, and it's sitting there right under our noses.

Roger Seheult (1:16)

Look, if I were to say, what is the single biggest intervention that someone can do right away that would show not only benefits in the short run, but also in the long run, and is the lowest hanging fruit, there's no question in my mind that sunlight is that intervention. With the benefits of modern science and technology, we can now actually literally get down to the molecular levels and show how getting out in sunlight can be tremendously beneficial on so many different levels.

Rangan Chatterjee (1:48)

That is such a bold statement in many ways. It's a statement that many people have probably not heard of before through the lens of health. But I guess the thing about sunlight, and I guess broadly speaking, natural light is that we've not really prioritized it or spoken enough about it for quite a while now, have we?

Roger Seheult (2:18)

That is true. And if we look back historically, this was not something that we ignored.

And look, I'm not telling you something that you don't already know. Florence Nightingale, who by many have been considered to be the founder of Modern Nursing, when she was taking care of English soldiers in Crimea, said, look, there's two things that I see that have the biggest impact on the health of my patients. Number one, fresh air. But a close second to that is light, sunlight, not just daylight, but direct sunlight. And she's quoted as saying that. And she was, no, she was there. She was at the bedside. She was known as the lady with the lamp. And that was well known at the time. And we have sort of forgotten about that.

Rangan Chatterjee (3:08)

So someone listening is getting so far that, look, light is important, okay? We know that getting outside is important. And I, like you, am really passionate that at the end of this conversation, people start taking their light exposure much more seriously.

But let's really try and unpick what is it about being outside that has all of these different aspects on our health.

Roger Seheult (3:36)

Absolutely. So when we look at the light that's coming from the sun, there's basically three types of light that we want to talk about. There is obviously the visible light, which you can see. And there is countless studies and decades of research that shows that visible light itself has a tremendous health benefit on the individual. Why? Number one, it prevents depression. So we know that people who live at high latitudes, who are not exposed to enough visible light, especially during the winter months when the days are short, when they're getting up before the sun gets up and they're getting home after the sun goes down, they are susceptible to seasonal affective disorder. And a very easy way of overcoming that particular issue is with visible light into the retina that stimulates a portion of the brain that prevents depression from happening. We also know that visible light, especially early in the morning when the sun is coming up, helps to ground and to establish a good circadian rhythm. There's something called the Zeitgeber that affects the timing of all of the processes in your body. So those two things right there are one of the, just the top of the list in terms of the things that visible light does when you get outside. Now, in terms of the two types of invisible light, when we go past violet, we get ultraviolet light.

And we all know that ultraviolet light, specifically ultraviolet light B is very important in the production of vitamin D3 in our skin. So that type of high energy, so this is short wavelength high energy, they have the energy to penetrate just very shallowly into the skin, which is where they're needed. But that's just one aspect of invisible light. Okay, so we've talked about visible light, we've talked about ultraviolet light. Let's go to the other extreme. So past red, this is also invisible, but this is very long wavelength. And this is what we call infrared. And today we're going to talk about red and infrared lights.