Background

Sleep disorders are common in people with bipolar disorder, with the largest changes in sleep patterns occurring during mania, the period of persistent and abnormally elevated energy or mood. There is some promising evidence that blue-blocking glasses, by blocking light in the blue and blue-green spectrum and thus preventing the suppression of melatonin production, may improve sleep for people with bipolar disorder in a manic phase. However, the available evidence is still preliminary.

The study

In this five-day single-blind randomized controlled trial, 20 people hospitalized with bipolar disorder and mania ages 18–70 years wore either blue-blocking or clear (placebo) glasses from 6:00 p.m. to 8:00 a.m., while continuing to receive their usual individualized treatment.

The primary outcomes, measured by an actigraph device worn on the wrist, were sleep efficiency (i.e., percentage of sleep during the main rest interval) and motor activity during sleep intervals. The secondary outcomes were total sleep time during the main rest interval, wake time after sleep onset, number of wake episodes, sleep fragmentation index (i.e., percentage of active time in sleep interval plus percentage of one-minute inactive bouts), sleep onset, sleep offset, and mid-time sleep.

The results

After five nights, sleep efficiency was higher (better), and motor activity and wake time were lower (better) in the blue-blocking glasses group.

Note

This trial reported the differences between groups at the end of the intervention. However, outcomes of interest are usually the differences between groups in the changes from baseline to the end of the intervention.

It’s also worth noting that while the authors state that the trial was preregistered, no preregistration records were found in the relevant database. Moreover, one of the authors is a shareholder in a company that manufactures blue-blocking glasses.

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This Study Summary was published on February 5, 2021.