Do blue light glasses work? Why the research says both yes and no

What did the Cochrane review find?

Cochrane is the most cited source whenever someone asks whether blue light glasses work, and rightly so. The 2023 review covered 17 randomised trials with 619 participants in total. The conclusions in brief:

• Eye strain from screen work: probably no short-term benefit compared with ordinary lenses.
• Sleep: the evidence is too weak, of very low certainty, to say whether the lenses make a difference.
• Retinal health: no studies gave an answer.
• Side effects: no consistent reports.

That is an honest and important summary. But it answers a question about one kind of lens, and that kind is not what most evening glasses are.

Why do the studies say different things?

The term blue light glasses covers two products that have little in common.

The first is clear lenses with a coating that reflects a small part of the blue. The review's lead author pointed out that such lenses typically filter about 10 to 25% of blue light. That is the type that dominates optician chains and most eye strain studies.

The second is tinted lenses, yellow, orange or red, that remove almost everything in a defined wavelength band. Our red lenses filter 99% between 400–550 nm. That is a difference in order of magnitude, not in shade.

The questions differ too. Eye strain at the screen is mainly linked to blinking less and focusing up close for long periods, not to blue light. Evening melatonin, on the other hand, is driven precisely by blue light between 446 and 477 nm. So a lens not helping with the first says little about what it does to the second.

What does research say about evening lenses?

In the lab, the picture is fairly consistent. Orange glasses stopped bright night-time light from suppressing melatonin in a Canadian study from 2006. Orange glasses in front of LED screens dampened the screen's effect on melatonin in teenagers in a Swiss study from 2015. Amber glasses worn two hours before bed gave better self-rated sleep and longer measured sleep time in adults with insomnia symptoms in an American study from 2018.

The studies are small, 13 to 14 participants each. And the step from dampened melatonin suppression to better sleep for every adult has not been proven. That is exactly what Cochrane says, and we agree. A 2019 study in PNAS also showed that sensitivity to evening light varies more than 50-fold between people, so the same lens can mean a lot to one person and little to another.

What do we promise, and what don't we?

We promise that the lens filters what we say, in the band we state. We do not promise less eye strain, fewer headaches or better sleep, because that has not been proven and we do not want you to buy anything on a claim that does not hold.

It is the same test you can put to any brand. Three questions are enough:

• What percentage, in which wavelength band? A figure without nanometres means nothing.
• Who measured it, and when? Ask for lens data or a test certificate.
• Which lens does the figure apply to? A brand with several lenses should give one figure per lens.

If it says 100% blocking, treat it as a red flag. No tinted lens lets exactly zero of a whole band through, and whoever writes that has rarely measured.

Who gets the most out of evening lenses?

People with screens or bright light in the last hours before bed who want to remove the light signal without switching everything off. People who work late, game in the evening or watch series in a bright living room. If you want the mechanism behind it, read Blue light and melatonin.