Yellow lenses at night for sleep: Not Such a Strange Idea

A previous post here referred readers to information on blue light as the particular form of light which affects our biological clock timing. That's why the newest light boxes, for light treatment of SAD (seasonal affective disorder), use just blue light.

But there's a little known flip-side to that story, about avoiding too much light at night, to preserve normal biological clock timing. I've written about this in an essay about "Dark Therapy", an interesting idea, but not well-tested.

Combining the blue-light story for SAD treatment with the Dark Therapy idea leads to a very odd -- but safe and cheap! -- idea for improving sleep. This would be most useful for people who have difficulty falling asleep because their mind is still wide awake; or people who have "rapid-cycling" bipolar disorder, which the dark-therapy research (such as we have to go on) suggests that quality darkness might be a "mood stabilizer" for them.

The combination of these two research threads suggests this: blocking exposure to blue light at night might be sufficient, rather than blocking all light as in the Dark Therapy approach, to allow easier falling off to sleep, or perhaps even gain the "mood stabilizer" effect of being in complete darkness. That's because of the selectivity of the biological clock for blue light, a story told in more detail on my page about why blue light is the one that matters in this business.

Blocking blue light is pretty easy -- and cheap -- because special glasses, with yellow lenses, for this purpose have already been developed, for other medical conditions . What I did not think had been done yet, in research, was to study the effect of those glasses on sleep.

But yesterday I found, courtesy of a reader (RH), that this approach has already been studied! A research team has already shown that using yellow-lensed glasses at night preserves normal biological clock timing even during late night light exposure. (Kayumov)

All that remains to be shown is that these lenses might actually help people fall asleep, by using them earlier in the evening, for people who can't get their mind to shut off when they're ready to try to go to sleep. Or that using these lenses might act like a "mood stabilizer" for people with rapid cycling bipolar disorder. That will be exciting research to watch for.

In the meantime I can imagine that some people are going to try it anyway, figuring that $40 for a pair of these glasses is worth a go (there are less expensive ones, but they block less blue light). If it seemed to work, it's pretty cheap -- and it's hard to imagine a risk that might go along with this, except looking rather geeky in the privacy of your own home at night. But hey, Jonathon, another reader, is already trying them at work! He works nights and is trying them to see if he can get to sleep easier after his shift when he uses the glasses. So far? He thinks they might be working but is going to conduct some on-off trials: 2 weeks with the glasses, 2 weeks without, to see if he can tell the difference. He's kindly sharing his results with me as he goes along. I'll post them.

For more on all this, try my essay on Light and Dark in Bipolar Disorder.