Blue-Blocking Glasses for Mania: A Negative Trial

A well-designed randomized trial fails to replicate the early promise of blue-blocking glasses for acute mania

STUDY: Fiedorowicz JG et al, Journal of Affective Disorders 2026;398:120910

STUDY TYPE: Randomized, double-blind, sham-controlled trial

FUNDING: Baszucki Brain Research Fund and the Milken Institute

Background

Bipolar disorder disrupts circadian rhythms, and blue light is the strongest signal that sets the biological clock. In the 1990’s, researchers at NIMH showed people could calm mania and rapid cycling by staying in a pitch dark room from 6 pm to 8 am. In theory, blocking blue light with special glasses achieves the same effect, and this approach treated mania in a randomized hospital trial from 2016. But the confirmation study here raises doubts.

The Study

42 inpatients with DSM-5 mania in Canada.

Randomized to blue-blocking glasses or lightly tinted control lenses.

Worn nightly from 6 p.m. to 8 a.m. for up to two weeks when not asleep, added to treatment as usual.

Blue-blocking glasses didn’t outperform control lenses. Mean YMRS scores fell in both groups, but the difference at week 2 favored the control group by just 2.1 points — a non-significant finding. Antipsychotic doses, benzodiazepine use, and all self-reported secondary outcomes were identical between groups. Adherence was good, at 80% mostly adherent or better.

Why Did It Fail?

• This study was double-blinded, while only the patients were blind to the treatment in the 2016 trial. That may explain the difference. Unblinded raters can sway the results.
• The placebo glasses in this trial may have blocked enough light to have a treatment effect
• They did not require patients sleep in a pitch dark room, and this may be a necessary part of the treatment. Even light as dim as a nightlight alters brain activity and mood when left on throughout the night. I am coordinating with the two study authors to find out how much light their patients were exposed to in the evening.

Practice Implications

1. Dark therapy still has support from randomized trials in insomnia, but the benefits in bipolar mania are not as robust as previously thought.
2. My take: Some patients respond very well, others not so much, and it likely depends on how much their circadian rhythm influences their mood. A pitch dark bedroom is essential to the therapy and I have seen patients improve as they seal up that part, usually by sleeping in the basement or investing in quality black-out curtains.
3. Getting the right glasses is also key.