Darkness Treats ManiaBright 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.

Background information

The idea behind light-blocking glasses is simple: light therapy reduces depression so it makes sense that dark therapy might help patients experiencing bipolar mania.

Psychiatric News summarized previous studies of this idea…

“In 1998 researchers at the National Institute of Mental Health tested this idea in a bipolar patient who was rapid cycling by putting him in a dark environment for 14 hours a day. They found that the patient’s mood and sleep patterns quickly stabilized. 

A few years later, Italian researchers conducted a pilot study with 16 bipolar inpatients and found that patients who had received the 14-hour dark therapy for three consecutive days, in addition to their regular medication, experienced a reduction in symptoms, required less medication, and were discharged earlier from the hospital.

While these studies pointed to the benefits of dark therapy, there were questions of how practical the technique might be outside of a hospital setting. A discovery in 2001 that the brain specifically uses the blue light wavelength to signal light/dark status suggested patients might also benefit from the “virtual darkness” created by blocking blue light.

Recognizing the tools to achieve this were already in place (welders have long made use of blue-blocking [also known as amber lenses] safety goggles to shield their eyes from intense blue welding sparks, and the goggles are known to increase visual clarity in the outdoors), Phelps began sending patients with bipolar disorder home with blue-blocking glasses.

According to Phelps, more than half of the bipolar patients he sees have reported improvements in manic symptoms, like insomnia, after using the blue-blocking glasses.”

Blue-blocking glasses have an antimanic effect

Preliminary data has suggested that there are antimanic effects of “dark therapy.” The authors of this study looked at the question of whether orange colored glasses (blue blockers) have the same effect.
24 hospitalized patients with mania, who also received usual anti-manic medications, were randomized to wear blue blocking glasses (BBs) or clear-lensed glasses from 6 p.m. to 8 a.m. for 7 consecutive days. The glasses were taken off when the lights were out.

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.