The Actual Use Case for Blue Light Glasses

I recently published a rather scathing indictment of blue light glasses marketers claiming that their products alleviate eye strain.

I’d like to clarify that blue light glasses do still have a use case. While they remain useless for preventing “digital eye strain,” they are a legitimate tool for reducing your exposure to sleep-disrupting light pollution at night.

Blue Light and the Circadian Rhythm

To understand where blue light glasses might fit into your health toolkit, let’s address why blue light is so consequential for human health in the first place.

Blue light is the primary environmental cue our bodies use to regulate our circadian rhythm. [1] The underlying physics are rather neat, so let’s take a look.

Our atmosphere scatters higher energy visible wavelengths (greens, blues, and purples) more than lower energy wavelengths. During sunrise and sunset — when the sun is oblique to the observer’s position on earth — there is more atmosphere for sunlight to go through before it reaches our eyes, meaning more of the higher-energy wavelengths are scattered before they can reach the observer.

As a result, high-energy wavelengths (“blue light”) naturally peak at solar noon for a given locale. Our bodies and brains have evolved to interpret exposure to blue light as a signal that it is mid day — and consequently, exposure to blue light at night antagonizes your ability to get healthy sleep. [5, 6]

Making Proper Use of Blue Light Glasses

First, let us acknowledge that blue light glasses do actually work. In many studies, they prevent the damage to sleep quality that nighttime light exposure causes. [2, 3, 4]

To the extent that you can control your light environment at night, you should prioritize that over the use of blue light glasses. Why opt for an accessory when you can simply use more circadian-friendly lighting after sunset? I use programmable smart lights to regulate the lighting environment in my own home, but there are alternatives; anything works as it’s relatively dim and reddish in hue.

There are sources of light pollution outside of your control, though. This is where blue-blocking glasses come in handy.

I use them when I’m driving at night to spare me the bright headlights leveled at my face (I swear truck headlight designers live by the mantra, “aim for their retinas” — no offense to truck owners). Another use case would be if you like talking walks around your neighborhood at night, in case your neighborhood has bright street lighting.