Bright Light Therapy in Major Depression and Anxiety

Bright light therapy has been in use for some years for insomnia and seasonal affective disorder, and results in those areas are very promising. Until recently, however, there has not been much data available about the use of bright light therapy for major depression.

A recent study, though small, was reported in a presentation at the American Psychological Association’s 2021 annual meeting. In it results showed that bright light therapy, using 7000 lux broad spectrum UV-blocked light in daily exposures of up to 40 minutes, resulted in significantly higher remission rates and significantly lower depression scores in the treatment group.

Dorothy Sit, MD, associate professor in the department of psychiatry and behavioral sciences at Northwestern University’s Feinberg School of Medicine, led the study, and reported the results. “[Bright light therapy] improves mood symptoms even in cases in which disruption in circadian rhythms is not the primary cause. Bright light therapy is used to reset and amplify circadian rhythms that have been disrupted, it is also used to improve alertness levels, provide an uplift in mood and restore functioning and social engagement, reversing the symptoms of depression and anxiety.”

Disruption in circadian rhythms is a frequent problem with mood disorders, and light therapy of different kinds has long been used in these cases. Blue light in the early morning, and the blocking of all blue light in the late evening have both been helpful for many people. The use of bright light therapy (7000 lux or more) has now been found to have an effect even in depression and anxiety that is not directly connected to circadian rhythm disruption.

The study, a randomized, placebo-controlled trial with 46 participants, all of whom had depression or bipolar I or II and were on stable anti-manic medications, gave daily treatments of 7000 lux bright light therapy to 23 participants, and 50 lux placebo to the others. The treatment group showed a significantly higher remission rate and significantly lower depression scores, with no mood polarity switches.

“We would suggest beginning with a 7,000-lux broad spectrum white light that produces a cooler 4,000 Kelvin bluish light and to initiate it at 15 minutes per day at the time between noon and 2:30 PM,” Sit said. “Each week, another 15 minutes should be added to reach a target of 45 minutes to 60 minutes. Maintenance therapy is essential, with antimanic therapy crucial to help patients avoid the risk for inducing mania or mixed symptoms.”

This study is also novel in looking at the use light therapy for indications including major depression, perinatal depression, ADD and others. We’ll keep monitoring this research for more news of interest to readers.


Sit D. Bright light therapy for treatment of bipolar disorder. Presented at: American Psychiatric Association Annual Meeting; May 1-3, 2021 (virtual meeting).