There are certain aspects of health, wellness and performance that get a lot of attention:
Food
Exercise
Sleep
Stress
These topics are the main focus for many, and rightfully so, they are often all dysregulated to some degree for a majority of the population. In addition it is easy to sell products around these topics as well.
Sometimes though there are other aspects of health, wellness, and performance that get less attention, but can have just as big or bigger impact. In fact the topic of this post can impact your food, exercise, sleep and stress.
What am I referring to?
Light!
Yup, light.
You certainly are not going to see magazines highlighting light as a way to optimize your health and wellness, but in my opinion, the light you are exposed to can play a major role in achieving any goal related to health, wellness, and performance.
Ancestrally we did not have to worry about light exposure, not like we had to worry about food, water, or shelter anyways. The sun came up and we had light for however long it lasted until finally the sun set and it went away. That is how we evolved, it was quite simple and elegant.
Today it is a different story, it doesn’t matter what the sun is doing, we can have light 24 hours a day or we can have darkness 24 hours a day. The problem is that the ability to control our light exposure is a relatively new phenomenon. It has only come about within the past 100 years or so and unfortunately our bodies are heavily influenced by the amount and timing of the light from the sun.
In my mind, the major reason why light exposure is so crucial to our health has to do with our circadian rhythm. Your circadian rhythm are the physical, mental, and behavior changes that follow a 24 hour cycle. The single biggest influencer of your circadian rhythm is…you guessed it, light! Once our circadian rhythm is dysregulated everything else is negatively affected.
The best example of this is the negative effect bright light at night can have on your sleep. I covered this specific topic in great depth in a past blog post, but in short, if you are exposed to an artificial Sun (aka your computer, TV, phone, or even overhead lights) after the real Sun has set, the hormonal cascade that sets you up for sleep gets thrown off and can make it more difficult to fall asleep when you go to bed.
On the opposite end of the spectrum we can use light exposure to enhance our sleep. To do this we can use light exposure at the start of our day to entrain our circadian rhythm. By seeing light soon after waking, it has the opposite effects on our hormones, in that it raises our awake hormones and lowers our sleep hormones. This now sets these hormones properly so they raise and lower at the proper times throughout the day.
Light does not only affect sleep though, it also can play a big role in our hunger hormones as well. Are you more likely to go rummaging through your pantry looking for food if you have all the lights on at night watching TV or if you are in a dimly lit room reading a book? Obviously we have all been there watching a show on TV at night and suddenly wondering if there is any ice cream in the freezer or cookies in the cabinet. I have never found myself thinking about food when I am relaxed reading a book by a lamp. Part of the reason is because the light from the bright light in the room is telling our body the Sun is still up, that means it’s an opportunity to get more calories in, and from a survival perspective, more calories equates to a better chance of survival [1].
Another area many people struggle with is their blood sugar regulation. With more than 80% of the US population metabolically unhealthy, this is a big problem. Turns out your exposure to light can both help and hinder your blood sugar control as well. In a fascinating study researchers found that when participants were exposed to dim light during the day and bright light at night before bed they had better blood sugar control at dinner than when participants were exposed to bright light during the day and dim light at night (which is the more natural exposure pattern). Researchers suspect that since we are better at handling carbohydrates during the daytime, the light exposure at night helped “trick” their body into handling carbohydrates better during dinner [2].
Below is a graph comparing the blood sugar response from the two groups.
https://link.springer.com/article/10.1007/s00125-021-05643-9
The statistically significant difference in blood sugar occurs only at the 90 minute mark after dinner where the dim day/bright evening participants averaged about 6.5 mmol/l or 115 mg/dl whereas the bright day/dim evening participants registered around 8mmol/l or 140 mg/dl. Actually even at 8mmol/l I would not consider that terrible, certainly not the best, but not the worst possible reading either. It’s also important to note that by the 150 minute mark both groups had the same blood sugar levels.
The main take away from the study is that we can see that light exposure can influence our metabolic health acutely. When we are eating a bunch of carbohydrates during the day without getting any light, especially natural light, our blood sugar control is going to be worse. Also to the point again about sleep, dysregulated sleep also negatively affects blood sugar control, again we are layering on the negative effects [3].
The last implication of light exposure I want to touch on is mood and energy. I can easily connect my mood to light exposure. If I find my mood and energy are not so good on a given day the first thing I ask myself is “When was the last time you were outside?” If it’s been quite a long time, or not at all, I immediately head outside for a walk. In almost every case I find myself feeling better and I think it partially has to do with the benefits of getting some bright light in my eyes. Research has shown this to be true, in that there are several different mechanisms in which lack of light exposure can cause mood disturbances [4].
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5299389/
Light exposure and timing might not be the sexiest topic to talk about when it comes to health, wellness, and performance, but I am convinced that it can make a huge difference. The best part is that it is free! The most powerful and beneficial light you can expose yourself to is the sun. Now there is a slight problem with that for some people during different parts of the year. There are places where the sun never shines for large portions of the day which makes getting any sunlight near impossible. While the invention of the light bulb is sighted as the cause of many people’s light exposure issues in this case, it can be quite beneficial. Devices like light boxes and ring lights can help you get a decent amount of light exposure even when the sun is not up. Again, you want to time this correctly….use them during the daytime, not the nighttime!
If light exposure at night is an issue for you, again technology can help out there as well. Blue light blocking glasses, light bulbs without blue light, technology on your phone and computers, and even devices you plug into your TV can all help reduce the harmful wavelengths of light that could disrupt your sleep.
This is a great example of modern technology helping us emulate our ancestral norms and improve our health! I for one am glad for all of these things because it allows me to enjoy many modern conveniences in the least detrimental way to me achieving my goals and maintaining my health. This is exactly the type of information I convey on a weekly basis via my newsletter. Actionable tips and tricks you can use to help align yourself with ancestral norms in today’s modern world. To get all this information straight to your inbox on a weekly basis use the form below to sign up for my newsletter.
- “Hunger hormone and sleep responses to the built-in blue-light filter ….” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6932843/. Accessed 10 Feb. 2022. ↑
- (2022, February 2). The influence of bright and dim light on substrate metabolism …. Retrieved February 11, 2022, from https://link.springer.com/article/10.1007/s00125-021-05643-9 ↑
- (n.d.). Relationships between sleep quality and glucose regulation in …. Retrieved February 11, 2022, from https://pubmed.ncbi.nlm.nih.gov/8770019/ ↑
- (2017, January 31). Timing of light exposure affects mood and brain circuits – NCBI. Retrieved February 11, 2022, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5299389/ ↑