Do blue light glasses work?

Whether blue light glasses do anything comes down to the color of the lenses. The clear "blue light" lenses sold for computer use filter so little blue light that they won't make much difference at night ¹. Dark amber and orange lenses block nearly all blue and blue-green light ². That's the kind most of the sleep studies used, worn in the evening ².

What each lens color blocks

Don't go by the "blue light" label on its own. When eight lenses sold as blue-light filtering were put to the test, six did little more than an ordinary clear lens to cut the light that holds back melatonin. The two that did the job both had a brown tint ¹. If you already own a pair, hold them up against a white wall. Lenses that look nearly clear are filtering very little ³.

Do blue light glasses help you sleep?

Some sleep studies found the glasses helped, and others found they made no difference ². They seem most useful for people who already have a sleep problem, like insomnia or a body clock that runs very late, and less so for healthy people who sleep well ². In a 2021 review of 24 sleep studies, people with sleep disorders fell asleep sooner when they wore the glasses in the evening, and so did travelers with jet lag and shift workers on changing schedules ⁴. Many of those studies were small, and some had no comparison group ⁴.

That isn't strong proof, but a pair is worth trying if you fly across time zones a lot or your shifts keep changing. Either way, I'd treat the glasses as the backup to a dimmer evening. Turning off the overhead lights and using lamps at night means less blue light reaches your eyes in the first place. On the nights you're on your phone or in front of the TV anyway, a dark pair blocks most of the blue coming off the screen ².

A pair is also handy on evenings when the lights aren't up to you, like a late night at the office, or a house where everyone else wants every light on ³.

Blue light glasses for eye strain

They're sold for tired eyes too, but in the short trials done so far, they didn't seem to make much difference to eye strain from computer work ⁵.

Sore eyes after a day at a screen mostly come from focusing up close for hours and from dry eyes ⁶. You also blink less while you're looking at a screen, which can dry them out even more ⁶. Taking regular breaks from the screen is one of the usual ways to deal with it ⁶. There's a simple version called 20-20-20: every 20 minutes, look at something about 20 feet away for 20 seconds ⁶. Most people won't remember to do that every 20 minutes, so tie it to things you already do. Each time you finish a call or send an email, look out the nearest window for a few seconds.

What to look for when you buy a pair

If the box or the website gives a number in nanometers (nm), it's telling you which colors of light the lenses block. The lenses in several sleep studies blocked nearly all light below about 530 to 550 nm ², so a figure like that is a good sign. Some labels stop at about 460 nm ³, which leaves out the blue-green just above it, the light that does the most to hold back melatonin ¹.

If the seller shows a chart of how much light gets through at each color, that tells you more than any single number. If there's no chart, go by the color of the lenses.

Then think about the fit. Glasses wearers can get a pair that fits over their own, or have their prescription made in a tinted lens. Either way, wraparound frames or side shields keep light from getting in around the edges ³.

How to wear them

I'd put the dark pair on for the hour before bed, when you're most likely to be on your phone or watching TV. Keep them next to the remote so they're there when you sit down. If you can, put them on earlier, when the lamps come on for the evening, since in several of the sleep studies people wore them for the last two or three hours before bed ².

Everything will look orange while they're on, and your phone screen will turn amber. Keep them on until you're in bed with the light off, and that includes brushing your teeth under the bathroom light.

In the daytime, real daylight comes first. When you're outside, leave both pairs off. Your body clock needs bright light during the day, ideally daylight outside ⁷. Indoors, at a screen or under LED and overhead lights, wear a yellow pair. A yellow tint takes some of the blue out of that light, and it's much lighter than the dark pair you wear at night. Take the yellow pair off in the morning, though, if you've turned the lights up or you're sitting by a bright lamp on purpose. Then in the evening, switch to the dark pair, for at least that last hour before bed.

The dark pair does its work in the hours before you sleep, whatever time that is ³. So after a night shift, you'd wear it at home in the morning before you go to bed ³.