100% blue-light-blocking glasses (amber-tinted) were found highly effective for treatment of acute mania, adjunctively to standard antimanic medications (Henriksen et al, 2016). Patients hospitalized for mania were instructed to wear their glasses from 6pm to 8am, other than when lights were out.
The control group wore gray-tinted lenses. All subjects were managed with medications as usual. Results were dramatic, with improvement seen within 3 days. The blue blocking glasses group ended up requiring substantially fewer sedating medications (hypnotics, anxiolytics, antipsychotics) than those randomized to the control group. The mechanism likely involves the suprachiasmatic nucleus of the hypothalamus, where melatonin also acts. The glasses used in the study are available from Lowbluelights.com.
The original approach started in the 1990s as (actual, not virtual) darkness therapy. This involved keeping the manic patient in pitch darkness from 6pm to 8am.
Blue is the shortest wavelength of light on the visible spectrum. The retina contains melanopsin photoreceptors that only detect blue light, projecting to the suprachiasmatic nucleus (SCN), which is the brain’s “master clock” in the hypothalamus. When these receptors are not exposed to blue light, the master clock thinks it is immersed in total darkness. Melatonin also signals to the SCN that it is dark, by binding MT1 and MT2 melatonin receptors.
For individuals with bipolar disorder, a strategy to prevent mania would involve wearing the glasses for 1–2 hours before bedtime (The Carlat Psychiatry Report, February 2019). Note the incidence of mania peaks in the spring when the amount of sunlight rapidly increases (Parker et al, 2018), typically in April.
Another way to trick to brain into thinking it’s dark out is to use blue light-blocking amber light bulbs (in an otherwise pitch-black room). Smart phones or tablets can be used in an otherwise dark room if set to filter blue light, which is call Night Mode (Android) or Night Shift (iOS), although this setting does not filter as much light as the glasses.
Blue-light-blocking glasses are also useful for insomnia in non-bipolar individuals when worn 1 to 2 hours prior to bedtime. No one should wear the glasses prior to 6 pm because this will mess with circadian rhythms and potentially disrupt mood. Wearing them in the morning could lead to depression. For depression, phototherapy with a light box would be the proper morning time treatment.
There is emerging evidence of a connection between blue light exposure and breast cancer, prostate cancer, obesity, and diabetes.
Main source:
Henriksen et al. Blue-blocking glasses as additive treatment for mania: a randomized placebo-controlled trial. Bipolar Disord. 2016 May;18[3]:221–32