Beyond Vision | Effects of Visible Light on Skin & Blood Vessels

Photo by Vladimir Fedotov on Unsplash

Background

I recently had a conversation with a colleague that was sparked by the blue-light blocking glasses that I wear.

We started discussing the impact that artificial LED light has on our eyes, circadian rhythm, and overall metabolic health. To be fair to this colleague, the conversation went further than I had expected before we hit a road-block. Because, most people reject outright the notion that isolated off-cycle blue light can impact your metabolism, insulin resistance, and blood sugar.

But, this article isn’t about the effects of light through the eyes.

This is about the impact of light on your body through non-visual photoreceptors that exist throughout your body.

The Basics

Before we dive into the details, we need to first set the groundwork so that you can appreciate the significance of the findings in the scientific literature.

First, we need to remember that beyond visible light, there are other electromagnetic radiations above and below this range.

What we call “visible” light, is the band of light between 380-750 nm (wavelength) which our nervous system uses to generate imagery in our mind.

It is interesting to note that because of the fact that we use this band of light to make images, it has limited function outside of image-formation. This is why light above and below (infrared and ultraviolet) this band has primarily physiologic consequences, and limited-to-no image forming capacity.

However, the mechanisms which control light entry into our eye/retina:

• control entry of other EM frequencies, and…

• are themselves impacted by visible light, a physiologic effect in itself

Thus, there is a path between some cellular function and “visible” light.

For example, there is a path between the impact of light entry into the eye and how your skin reacts to UVB light. For a deep dive, check out this Twitter thread. The key is that early morning light (Infrared and a little UVA) generates the Nitric Oxide we need to facilitate subsequent UVB-dependent melanin production (and other important related molecules).