Stabilizing circadian rhythms can be helpful with bipolar disorder, and there’s even one treatment called (straightforwardly) “dark therapy”, in which complete darkness is used to reset the circadian clock (there’s some limited data supporting this). Jim Phelps of bipolar site psycheducation.org has written about circadian rhythms and dark therapy, and now has a paper out looking to get around the issue where nobody actually wants to be in total darkness for long periods of time except maybe when they’re sleeping.
The paper doesn’t have a controlled trial, just a series of case studies where people with bipolar disorder were able to fall asleep faster when they were undergoing treatment involving amber-tinted safety goggles, which block some wavelengths of light that knock melatonin levels down (e.g., the goggles keep melatonin at night-time levels).
So, don’t go out and buy dorky goggles just yet, and maybe not at all depending on how the evidence turns out, but if you’re interested in the circadian-rhythm angle this might be something to keep an eye on.
