Bright light is one of the most rapidly effective treatments for depression and may be helpful for depression even in people without a clear seasonal pattern (winter depression). A recent study suggests that it may also be true that darkness treats mania.
The portion of the light spectrum that affects circadian rhythms the most strongly is blue light, which is why the GoLite, which only puts out blue light, is so effective in treating seasonal depression. The authors of this study examined whether glasses that blocked blue light might be helpful in treating mania.
Blue-blocking glasses have an antimanic effect
The study looked at the impact of this intervention on physical activity measured with actigraphy (you probably carry one of these with you since most smart phones measure physical activity this way) and daily ratings of mania by clinicians.
Less medication was needed in those who wore the blue blocking glasses.
Mania scores were significantly lower after 3 days of BBs and continued to improve through 7 days. There was a very large effect size (number needed to treat (NNT), >1.5). NNT is one of the most useful ways of assessing the impact of an intervention. The smaller the number the greater the effect of the treatment. To put this finding into context, the NNT in all trials of atypical antipsychotics for mania was 5. In other words, in this one small study, BBs were much more effective than atypical antipsychotics.
Individual symptoms improved as well, especially irritability and racing thoughts. After the second night, average activity was lower.
Two patients using BBs experienced emerging depressive symptoms.One improved after decreasing BB duration by 2 hours; the other stopped it for one night, and mood rapidly elevated. One patient and three healthy controls reported headaches.
Henriksen TE et al. Blue-blocking glasses as additive treatment for mania: A randomized placebo-controlled trial. Bipolar Disord 2016 May; 18:221. (http://dx.doi.org/10.1111/bdi.12390)
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