Blue light plays an important role in setting your circadian rhythm. And the best part is, it’s very easy to measure. As a result, we have a ton of data on how our exposure to blue light impacts our circadian rhythm.
Exposure to blue light during the day triggers a protein in our eyes called melanopsin. Consequently, melanopsin blocks the production of melatonin by our pineal gland.
On the other hand, as the Sun goes down and our exposure to blue light decreases, we release the brakes on the pineal gland and it starts pumping out melatonin. As a result, melatonin helps us fall asleep.
This simple set up is wonderful for studies on how blue light impacts our central circadian clock. You’ve likely seen many articles on circadian rhythms and blue light.
But, this gives people the perception that blue light is the most important factor for circadian rhythm. We really don’t know if that’s the case.
In today’s video blog we cover the many different factors in light that control our circadian rhythms.
Blue light, yellow light, early light, late light: For circadian rhythm, it all matters
Our exposure to many aspects of light throughout the day impacts our circadian rhythms. Different colors, intensities, duration of exposure, and combinations of thereof matter. Even the time of day you are exposed and your long-term light history play important roles.
Like me, you probably read about the importance of blue light and ran out and bought some blue blockers. Blue blockers are glasses that filter out the blue light in your environment, so they will absolutely increase your melatonin levels.
But is this really the most important thing? What if I were to tell you that people who lack a pineal gland have relatively normal circadian rhythms? It’s true, even in the absence of the blue light generated signal from melatonin, they have normal circadian rhythms.
However, what happens if selectively filtering out a single wavelength of light(Blue) disrupts some other important signal? We actually have data that this may be the case. For example, it negatively impacts important transitions that happen at twilight.
The relationship between light and circadian rhythms is very complex, so complex that we’ve only scratched the surface. This is why addressing blue light is an attractive approach to people, it’s easy and there’s data to back it up. On the other hand, simple isn’t always most effective.
But if results are what you’re looking for, you wanna pay attention to other factors as well. Luckily, it’s pretty easy to incorporate these various factors.
How light controls our circadian rhythm
In today’s video blog we cover how light controls our circadian rhythms. We talk about the many factors in light that play a role, and how the day/night light cycle has natural but consistent variations in all these factors.
Next, we cover how the eye perceives light, and finish off with 4 slides of takeaways to help you control your light environment. Most importantly, we chat about important times for daily light exposure, how to arrange your nighttime light environment, best types of light at night, how to safely use devices at night, and more!
As always, to help you navigate the video, here are the timestamps of the different topics covered:
(00:00) Intro-What light does for our circadian clock
(5:11) Myth vs reality with blue light
(10:02) Different aspects of light that affect circadian rhythms
(27:36) How light affects your circadian rhythm
(34:20) Individual differences in light sensitivity
(41:21) How to create the proper daily light environment
We hope this video helps you understand why your light environment is important. Above all, we hope it helps you properly leverage the science of circadian rhythms for your health!