(updated 2/2019)

Dark Therapy is for insomnia and attention problems, as well as mood. Although this page is written mostly for people with complex depressions, learning more about Dark Therapy will be useful for any of these issues.

Short version: good evidence suggests that for their health, some people simply need to spend more time in the dark. But you don’t have to turn off all the lights. If you’re impatient, jump to learning how to cheat.  Otherwise, here’s the whole story of Dark Therapy.

A single case began Dark Therapy

Here’s a story from a great research team 

Dark Therapy as treatment for rapid cycling bipolar disorder
Original Dark Therapy case

In the graph you see a 3 year record of sleep and mood for a man with rapid-cycling bipolar disorder. On the right, marked by blue, you see a mood record that shows obvious and frequent cycling.  When the line goes right, that’s a manic phase. When it goes left of the center line, that’s depression.

On the left, marked by red, you see a sleep record (don’t bother trying to figure out what it means. There’s a pattern, which will be obvious in a minute).

Next to it, marked by purple , is the total amount of sleep per 24 hours (to the right is a lot, to the left is a little — again, it’s the pattern that matters).

If you look closely you can see that the amount of sleep (under the purple arrow) closely matches the mood curve: less sleep during manic peaks; and more sleep during the depressive phases.

The main point so far is to see the rapid and obvious cycling.

Treated with no change in medications

After treatment with Dark Therapy, look at this improvement
Outcome of Dark Therapy treatment

Here is the same record, starting from the severe depressive episode marked before (***), and now continuing into treatment — beginning at * . Notice that almost as soon as treatment begins, his sleep becomes more organized (neat black and gray bands); his total sleep per 24 hours starts to be consistent * ; and his mood curve starts to settle toward the middle * .

So, what was this treatment? Not pills, those didn’t change. It wasn’t easy: with his consent, the research team required this man to stay in darkness 14 hours every night, from 6 pm to 8 am the next morning. (After a few weeks they eased up: only 10 hours of “enforced darkness”).

How could “darkness” treat rapid cycling? And what does this mean for your treatment?

How does Dark Therapy treat rapid cycling?

To understand this patient’s response to this treatment, we must turn to our “biological clock”. (For a stunning example of how powerful this clock is, and how important in bipolar disorder, have a look at an example of a patient who cycled every 24 hours, first a day up, then a day down — with matching laboratory evidence of cycling: hormones, even handwriting!) The research team theorized that in rapid cyclers, their clocks have lost the ability to respond to the timing of natural day and night.

They knew that the a specific part of the hypothalamus, the suprachiasmatic nucleus (SCN), has direct nerve connections from the eyes. It gets direct signals about how much light is out there. And it has been shown to be the main location of the “biological clock” in many animals, including humans. They thought that the SCN might get “desensitized” in some susceptible people by too much light, namely too much artificial light at night.

They hoped that the could reverse this with its opposite — enforced darkness at night. They believed that the SCN could become more sensitive again, if given this treatment. Perhaps then it would then have more influence over the body’s cycling, as it is supposed to?

They set out to test this idea by taking a person with rapid cycling and helping him get “plenty of dark”. In fact, they made sure that’s what he got! Every night he came to their research program and went into a room with a bed, but no lights. He didn’t have to sleep, but he couldn’t do anything — there was no light to read by, no television, no phone: “enforced bed rest and darkness”. You can see how well this worked for him from the curves above.

What does this mean for your treatment?

I hope the implications are obvious: you might be able to get by with less medication if you avoid late evening light and activity.  This is not a cute idea, or guesswork: a formal randomized trial was published last year. It strongly supports darkness as a bipolar treatment.

And darkness is one treatment that has very few risks (the other is exercise, if you haven’t read about that yet). And it would be easy to move at least a little bit in the direction of less artificial light, and less late evening electronics. At worst, you’d spend some evenings lying there in the dark. I know from my patients’ reports that this is not trivial: it means lying there with your thoughts, which can be pretty rough. However, look at this guy’s curves again — he did it, and look how fast things started changing for him (on no medications):

Notice how Dark Therapy improves sleep even before mood
Dark Therapy: sleep record

I don’t recommend that you try to treat yourself with darkness alone, that’s not the point. Rather, I suggest that you look at how much artificial light you’re getting, particularly late at night, and try to cut back on that. But you can cheat…

Have your darkness and eat it too

There’s the trick. You may have heard of this. I’d love for you to really understand the details, because the whole story is so important.  But the short version is:  only blue light sets your clock. Get rid of it, and your body thinks you’re in the dark! A $10 pair of amber safety glasses can take out enough blue. Put them on at 8 pm and you can have your lights and electronics.

Here’s the whole story of blue light and amber lenses (including where to buy the glasses most cheaply).

Other relevant pages: