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Dark Therapy with Blue-Blocking Lenses

last updated 3/17/25

Darkness can be a mood stabilizer. Ah, but darkness is no fun (or worse, for some people). Here’s a way to have more darkness without interfering with your life.

Light is an antidepressant

No doubt about it. Light has an antidepressant effect. But antidepressants can make mood cycling and mixed states worse for some people. So can light, if it comes at the wrong time. At the right time it’s useful, almost essential. But in modern electrically lit houses, many of us need to get more darkness.

Darkness is a mood stabilizer

Darkness can act just like a medication, decreasing cycling and mixing of mood and energy. Like a medication, this doesn’t work for everyone, but here’s the big difference: increasing your time in darkness has no side effects and only one risk (a few people can get more depressed, but that’s easy to fix: turn on the lights again, right?).

If you’re skeptical (that’s good) you might want to see some evidence that getting more darkness “really works”. But since “Dark Therapy” is cheap and harmless and easy and doesn’t even require giving up nighttime light, perhaps a whole lot of good evidence is not so necessary for this idea. (So I put the Evidence stuff at the bottom of this page…)

Darkness without turning off the lights

Huh? How’s that possible? It’s a great story. This is the short version. The long version is linked at the bottom of this page. Here’s the trick:

  1. All colors of light are not equal.
  2. Only blue light sets your body’s clock, your “circadian rhythm”, to DAYTIME.
  3. Blocking blue light makes your body think you’re in the dark.
  4. You can block blue light with $10 amber safety glasses, creating “virtual darkness”.
  5. Wearing theses glasses for 1-2 hours before bed improves sleep.

What is “virtual darkness”?

When the sun goes down, it “should” be dark, right? It’s not natural to have light at night. So all we’re going to do here is help you live in a more natural world.

You could just keep the lights off. But who wants to do that? Besides, you’ve got to study, or help the kids study, or get ready for work tomorrow. And, yes, I know what you’re really doing: you want to look at one of those screens, don’t you. Television, computer, tablet, phone. Fine, you can have them. Just block the blue light coming from them and your house lights.

No, it’s not enough to use those low-blue functions on the electronic devices. They still put out a whole lot of blue. You can test that if you don’t believe me. Just put on blue-blocker glasses and watch the change. (For example, even in NightShift mode, the blue on your Apple phone is still there, until you put on the lenses. To test the glasses themselves, look at the blue pilot light on your stereo or other electronic device. That light will disappear when you put on fully blue-blocking lenses).

Using virtual darkness for sleep or mood

Make your world more natural. Get rid of the blue light an hour or two before bed. That’s all it takes. (Well, for treating mania they used 4 hours, not just one or two. But for use as a routine mood stabilizer, even an hour will help.)

So, here’s the process:

  • One or two hours before bed, put on your blue-blocking lenses
  • When the house lights are off, take off the lenses
  • Make sure your bedroom is truly dark.
  • If you need a night-light, use a no-blue one (amber color).

Details:

  • The lenses are not super-comfortable, the cheap ones anyway. Most people will only use them for a few weeks to get their mood symptoms under control. Or when symptoms are getting out of control.
  • You could just turn off the lights instead of wearing the glasses. Most people figure out that by turning off their screen devices, including television, at least an hour before bed, they sleep better. Remember, “natural” would be best. You will figure out how much light-at-night you can handle. Until then, use the blue-blockers.
  • Making your bedroom really dark is not easy. Use curtains, or if you have to, tin foil the windows. Really.
  • Sleep masks? Good thought, but they will interfere with seeing the light arrive in the morning, and you need that too. Sleep masks are great for travel-at-night, though.
  • Amber night lights? Great idea. They’re cheap too. ($13 for two of this version)
  • But now it’s dark in your bedroom when the sun is coming up, oops. If you’ve taken all these steps, you will need a “dawn simulator”. More on those below.

Are there any risks? (only one, easy fix)

In the randomized trial of blue-blocking glasses for inpatient mania, one guy got depressed after only a night or two. No problem: stop using the glasses. In another night or two, he was no longer depressed (still manic, in fact, but less than when he started). The glasses’ effect can be very fast. Not for everyone though. In general you can only shift your biological clock about 45-60 minutes per night, and that’s part of what the glasses do.

What kind of glasses should I buy

Many choices now. Not so many back in 2008 when I suggested this might work. But then a smart nurse practitioner colleague found that cheap safety glasses for laser welding were good blue-blockers. So you might as well start there. If they work great, maybe later check out some more comfortable, more expensive models.

  • Fit-over-glasses model: “Mozeeda” safety glasses , $11 (replaces the UVEX model I can’t find anymore)
  • More stylish if you don’t wear glasses: Pyramex S2540S, $3 . (also replaces an unavailable UVEX model)

How a dawn simulator fits in

If you’ve made your bedroom really dark (it’s like a cave now. Oh, how natural), you will need an artificial dawn in the morning. Fine, we can do that too. A “dawn simulator” gradually increases the light from a bedside lamp over about 30 minutes before you wake up. No sitting in front of a light box. The light reaches your brain through your eyelid. Zero risk — unless you have a bed partner with a later rise-time, who might not appreciate dawn showing up on your schedule! More on dawn simulators.

Show me the evidence

Since Virtual Darkness is cheap and nearly harmless — why wait for more evidence? I’m not making any money selling or otherwise promoting this idea (good that you wondered, though). But I do fret that it’s not absolutely routine to recommend and try it! Here’s the main evidence so far:

Two “randomized trials” (this one and this one) comparing Dark Therapy plus routine treatment to routine treatment alone have shown darkness to have a strong and very rapid anti-manic effect. Dark Therapy (using real or virtual darkness) has not been directly tested as a mood stabilizer (to stay well, not just get out of a manic episode). A randomized trial for that is just getting started.

But lots of other evidence, including my clinical experience, suggests that blue-blocking lenses do indeed act just like lithium and lamotrigine, stabilizing mood. Not for everyone. One patient said he found them most useful as safety glasses when mowing his lawn! If they were expensive or dangerous we might need more evidence that they really work better than a placebo. But they’re not expensive or dangerous. I used to give them away to patients to try (back when I was still seeing patients). They’re that good an idea.

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