Dark Therapy

A simple, natural way to fix one of the underlying causes of bipolar disorder. Here’s how dark therapy began, and where it is today.

A Single Case Makes an Important Point

Here’s a story from the great research team at the National Institutes of Mental Health (NIMH), originally reported in Bipolar Network News from which the graphic below derives; later published by Wehr and colleagues.



Here you see a 3 year record of sleep and mood for a man with rapid-cycling bipolar disorder. How the NIMH managed to get these recordings I don’t know. On the left, marked by red, you see a sleep record (don’t bother trying to figure out what it means, just look at the 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).

On the right, marked by blue , you see a mood record that shows obvious and frequent cycling from manic peaks to depressive lows (the lows are slightly longer, you can see, especially the one marked ***).

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

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

Treated with No Medications


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? NO MEDICATIONS. That sounds great, doesn’t it? But it wasn’t easy: the NIMH 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 Darkness 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 — and has matching laboratory evidence of cycling (hormones, even handwriting!) The NIMH 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. (For much more information on how light and darkness affect bipolar disorder through the biological clock, start with my page on Bipolar Disorder: Light and Darkness, and try some of the links there as well — cool stuff!)

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, on no medications, 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.

Nocturnal light – even at low levels – causes depression, impedes learning, and has detrimental effects on the brain. It lowers brain protective factors like BDNF and shortens the neuronal connections (“dendritic spines”) involved in learning, memory, and concentration (Bedrosian, 2013)

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. Unfortunately, because there is no pharmaceutical manufacturer selling “darkness”, we don’t have lots of funding to support research on this treatment. So there have not been formal tests of this approach, except a second case report,an Italian study, details below — and now (2014) a Norwegian team studying the “have your darkness and eat it too” approach.

On the other hand, 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):



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.


Dark Therapy in Bipolar: The Big Study

For two decades, we only had a handful of studies supporting dark therapy, and none of them were well-designed. They showed that it was safe, and probably worked, but they lacked the gold-standard in medical research: The randomized, placebo-controlled trial.Barbini

That finally arrived in 2016. A Norwegian team lead by Tone Henrickson tested out dark therapy in 32 patients who came to the hospital for bipolar mania. Within a week, they improved significantly (without any med changes!) compared to a placebo group. Dark therapy was pretty powerful in this study, clocking in with an large “effect size” (a measure of how much better it worked than placebo. Here’s what else they found:

  1. The patients improved even though they didn’t sleep more. Actually, the ones who got dark therapy slept a little less than the placebo group.
  2. Although they didn’t sleep more, their sleep patterns became more regular, and their sleep quality improved (fewer night-time awakenings, deeper sleep, and less time tossing and turning in bed – what sleep scientists call “sleep efficiency).

Dark Therapy for the Rest of Us

The researchers at NIMH who discovered dark therapy didn’t set out to use it for bipolar disorder at first. Instead, they started with regular insomnia, and it worked. Imagine staying in a pitch-dark room from 6 pm to 8 am – that’s bound to do something for sleep! Here’s what we know about dark therapy from the handful of studies out there:

  1. It prevented postpartum depression (after pregnancy).
  2. It deepened sleep an improved next-day concentration
  3. It may, or may not, treat depression

That last one is an unknown. It would make sense that dark therapy could help depression. After all, nocturnal light as faint as a nightlight increases the risk of depression, and it prevented depression in new mothers. But we only have one study so far that tested dark therapy out in active depression, and it didn’t work. However, there is a big caveat to that failing. The glasses they used were uncomfortable, and the patients didn’t always wear them.

On a more speculative level, dark therapy may reduce weight gain and lower the risks of cancer, heart disease, and diabetes (this hasn’t been proven, but we do know that nocturnal light increases those risks).

Dark Therapy the Easy Way

So far dark therapy sounds great. It works, it’s natural, and it gets to one of the core causes of bipolar disorder. But who can stand to be in a pitch dark room all night long? Fortunately there’s an easier way. You can use blue light filtering glasses like the ones below – when you put them on your brain will think it’s in a pitch dark room (as explained in this piece).

To learn how to use them, read our six-step guide to dark therapy.

Uvex Skyper S1933X This low cost model (around $10) is a good starting place, but more comfortable models are at LowBlueLights.com (around $50).

Learn more about how to get your bedroom pitch dark (and how to use low blue light night lights).

Other relevant pages:

(updated 11/2020)