Evening darkness — or blue-light blocking glasses — can help regulate circadian rhythms and promote steadier mood states.
Did you know that darkness itself can be a mood treatment? Many people don’t get enough of it — but here’s the good news: You can cheat!
Let’s start with a famous case, then a famous graph. The main idea here is that dark therapy is a nearly harmless, $10 tool that many people can use. It might help a lot, and enable you to use fewer psychiatric medications. Or, it could be a total dud, but it won’t have cost you much, and you’ll have learned some cool stuff.
The (Should Be) Famous Case of Darkness Treating Rapid Cycling
Mr. D tried at least 10 medications, many in combination, but continued to have 8 to 10 episodes of mania and depression per year, with no “normal” phases in between. Finally, he was treated at the National Institute of Mental Health (NIMH) for several years.
Below you see three years of his mood record. Ups on the graph are manic phases, downs are depressions.
At the asterisk, the NIMH team added a new treatment. Within a few weeks, his mood began to stabilize, then became really steady for over a year — with no new medications.
What was this magic treatment? Dark therapy.
With his consent, they put him in a completely darkened room for 14 hours per night, from 6 p.m. to 8 a.m. the next day. No phone, no lights. After three months, he moved back home but continued to experience complete darkness at night, gradually reducing it to 10 hours (10 p.m. to 8 a.m.). Darkness functioned as a mood stabilizer in this remarkable case study.
The (Should Be) Famous Graph Showing Darkness Calming Mania
Years later, researchers in Denmark studied dark therapy in patients hospitalized with a manic episode. (The long delay shows how slow research can be when there’s no pharmaceutical company to fund it.) Patients who agreed to participate were given special glasses to wear from 6 p.m. until going to bed in rooms that remained dark until 8 a.m. the next day.
Glasses? Yes — simple $10 safety glasses you can wear over regular ones. This is the “cheat”: Amber-colored lenses block blue light. And it’s blue light — and only blue light — that sets your biological clock. Blue light tells your brain, “It’s daytime!” When wearing
“blue blockers” (BB), no blue light reaches the part of the eye that signals day or night. As a result, the brain assumes, “it must be dark.”
That’s the key idea — simple, but powerful. Now we can try dark therapy just by putting on a pair of BB safety glasses. Half of the patients in the hospital study received BB lenses, while the other half received grey-colored (control) lenses. These glasses were worn from 6 p.m. until the hospital’s room lights went dark until 8 a.m. the next day. The researchers used a daily scale for manic symptoms called the YMRS (Young Mania Rating Scale) to measure progress. Look what happened:
As you can see, in Denmark, they’re not too aggressive with anti-manic medications. During the first week, the control group showed little change on the YMRS, while the BB lens group showed steady improvement. They were discharged from the hospital sooner and received only about half as many antipsychotic medications as the control group.
Before You Try the Glasses
Before you think about getting some amber lenses, first make sure that your bedroom is dark — too dark to read in; the darker, the better. If you have to, put tin foil on the windows. (You can explain why to your neighbors later!)
Now it’s so dark in there that you’ll need some light to move around. Okay, get amber-colored nightlights if you need them. They don’t emit blue light, which, remember, is the one part of the light spectrum that says, “it’s daytime.” Once you’ve done that, you’ve got real darkness — and you might find you don’t even need amber lenses.
Reasons to Try BB Glasses
Here are some reasons to try wearing blue blockers for an hour (or preferably two) before you turn out the lights:
- You have difficulty slowing your mind down before bed and falling asleep.
- You have to stay up late because of someone else’s schedule.
- You just can’t bear missing out on late-night television (ahem).
- One of the most common: lying awake, you have awful thoughts, so you stay up late hoping to fall asleep quickly.
In my experience, about half of the people with these reasons find blue blockers helpful. They don’t wear them all the time, but when sleep is not going well, they use them again for a while. The other half, sorry, no benefit. But it didn’t cost much.
You can also use them if you’re one of those people who reads in the middle of the night (or watches television — it’s easier to be mindless, but not as helpful for getting back to sleep).
One Risk of BB Glasses
There’s one risk to know about before you try BB glasses as a mood stabilizer. In the Denmark study, one fellow went quickly from mania into depression. Fortunately, he came right out of it when the use of the glasses was stopped. For him, dark therapy worked a little too well as an anti-manic tool. But that was 14 hours of darkness. What would, say, 10 hours have done? We don’t know. Just be alert for a sudden big downturn in mood — it could be related to the BB glasses.
Using Dark Therapy
As you’ve seen here, dark therapy can be used in two ways: as an anti-manic treatment (14 hours per night) or as a mood stabilizer (10 hours: eight hours of sleep time plus two hours before that wearing BB glasses).
Because dark therapy is so unlikely to harm you, I can describe it freely. Still, it’s best to talk about it with your treatment team so they’re aware of what you’re doing.
Dark therapy is really just one part of a bigger mood stabilizing treatment: social rhythm therapy (SRT). I’ll present SRT in a later essay. But the best starting point for SRT is establishing regular sleep — having a consistent bedtime and wake time. Dark therapy can help get that routine going.
Which BB glasses?
You can spend $100 if you want, but even inexpensive pairs will work if they block enough blue light. As of this writing, these are available (not including shipping):
For fitting over your glasses:
If you don’t wear glasses:
I hope that some parts of this dark therapy idea work for you.
References:
- Phelps J. Dark Therapy for Bipolar Disorder Using Amber Lenses for Blue Light Blockade. Medical Hypotheses. 2008.
- Wehr TA et al. Treatment of Rapidly Cycling Bipolar Patient by Using Extended Bed Rest and Darkness to Stabilize the Timing and Duration of Sleep. Biological Psychiatry. June 1, 1998.
- Henriksen TEG et al. Blue-Blocking Glasses as Additive Treatment for Mania: A Randomized Placebo-Controlled Trial. Bipolar Disorders. May 26, 2016.