Don’t go into the light!

June 12, 2007

I finished reading this article, from PsychEducation.org, about how dark therapy might actually supplement (if not actually supplant) medication for managing bipolar disorder. The author of this article falls back on a few different studies that were done, each demonstrating a link between enforced periods of darkness and a reduction in swinging moods. The suggested reason for why this happens, why people with bipolar disorder might benefit from dark therapy, rather than the light therapy given to people with SAD, has to do with our biological clocks. It was a theorized faulty biological clock that researchers were hoping to treat with dark therapy in the first study, as shown by this quote:

“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.”

The results in this study were dramatic (as the original article shows) – the sleep pattern and cycling (the patient for the first study was a rapid cycler) normalized rapidly, and sans medication. The problem I have with this is that there are two things I can think of speaking against the logic of light hitting the hypothalamus being a causal factor for bipolar disorder, particularly artificial light: blind people; and the fact that records of this disorder go back thousands of years before the advent of artificial lighting. I don’t dispute the results – just the assumption that artificial lighting has any role in the cause for bipolar disorder, and possibly that it was lack of light (rather than other factors) that caused these results.

The other study referenced by this article, of 32 manic bipolars in Italy, also showed a correlation between dark therapy and some reduction in symptoms – and in this case the therapy was only used for a period of three nights. While the results weren’t quite as dramatic, the fact that these patients were in a manic phase critical enough to require hospitalization should be taken into consideration – once my genie uncorks himself, I’d be amazed with the kinds of results demonstrated in the Italian study, too.

For myself, I’ve always been sensitive to light. Although it’s not as true now as it was in my youth, I still have relatively good night vision – and the headaches I get from going outside on a sunny day without any kind of eye protection (sunglasses or at the minimum a hat) can be brutal. I have almost always preferred moving around at night – along with light sensitivity, I’m also a fan of cooler temperatures. To fall asleep properly, I have to be exhausted, and in the cold and in the dark. This means it’s usually late into the night before I start thinking about bed, if I bother to think about it at all. That my Circadian rhythms are out of whack is not something I would dispute with anyone, and I would definitely welcome definitive research proving a link between bipolar disorder and light sensitivity. But with these studies, and with what I consider to be flaws in their hypothetical assumptions about light and bipolar disorder, I wonder if it was the actual routine, rather than the light, that made the difference?



  1. I too have read quite a bit about dark therapy but it was very difficult for me to acheive this due to having a family.
    I looked at blue blocking glasses to provide ‘virtual darkness’ but commerical ones were very expensive and amber sunglasses didn’t work well.
    So I made my own. I put them on 2 hours before bed and after 30 minunte could feel myself relaxing. By bedtime I was ready to sleep. Obvoulsy part of my sleep problem was melatonin and body clock based.
    I made an extra 50 pairs as cheap as I possibly can and put them up on eBay for others to try. If they go well, I’ll make some more.

    You can find them here:


    Best of luck.


  2. It’s why I always where polarized sunglasses in the Summer. I honestly think it helps me.

  3. I am so relieved to hear about this I am Bipolar 1, have severe light sensitivity and get fits as well with strobe lights , it is so bad I have to wear polarized glasses inside my office building , imagine all the jokes but wearing glasses all the time helps with the nausea coming on and staying when the lights are to bright. I had Earlin lenses before but find polarised to be better. The meds does make it worse as well.

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