Bright light treatment either alone or combined with an antidepressant was an effective and well tolerated treatment for adults with nonseasonal major depressive disorder (MDD) in a randomized clinical trial, according to an article published online by JAMA Psychiatry.

MDD is among the leading causes of disability worldwide and is associated with impaired quality of life and an increased risk of death. Treatments include psychotherapies and antidepressants but remission rates remain low so more therapeutic options are needed. Light therapy has been effective treatment for seasonal affective disorder (SAD).

Raymond W. Lam, M.D., of the University of British Columbia, Vancouver, Canada, and coauthors conducted a double-blind and placebo-and-sham-controlled trial to test the efficacy of light treatment alone and in combination with fluoxetine hydrochloride compared with a placebo treatment involving an inactive device and a placebo pill.

The eight-week trial randomized 122 patients: light therapy (30 minutes/daily exposure to a fluorescent light box as soon as possible after awakening) and placebo pill (n=32); fluoxetine (20 mg/daily) and placebo device (a negative ion generator, n=31); combination light and fluoxetine treatment (n=29); or placebo device and placebo pill (n=30). The change in a common depression rating scale score was the study's primary outcomes.

The authors report combination therapy and light therapy alone were superior to placebo but fluoxetine alone was not superior to placebo.

Why light therapy appears to work is still unknown but hypotheses in SAD involve resynchronizing circadian rhythms. Nonseasonal MDD also may be associated with disturbances in the circadian rhythms, according to the authors.

The authors note limitations of the study including not measuring patients' natural light exposure.

"Further studies exploring mediators and moderators of response will be important," the study concludes.