Bright light therapy works well in patients with unipolar depression, evening chronotype

The use of bright light therapy with gradual advance protocol in the adjunctive setting appears to be beneficial to patients with nonseasonal unipolar depression and evening chronotype, with a study showing that it rapidly induces remission in most patients.

A total of 93 patients (mean age 46.4 years, 80 percent female) were randomized to undergo 5 weeks of either bright white light therapy or dim red light with the same advancement protocol. All patients were followed for 5 months after treatment.

Primary efficacy endpoints were remission rate and the severity of depression. Researchers used Kaplan–Meier survival, Cox proportional hazard, and linear mixed models in the analyses.

The cumulative remission rate was higher with bright light therapy than with dim red light (67.4 percent vs 46.7 percent). Time to remission was also shorter among patients who received bright white light (log-rank test, p=0.024).

Cox proportional analysis showed that the probability of achieving remission was about twofold higher in the bright light therapy group than in the dim red light group (hazard ratio, 1.9, 95 percent confidence interval, 1.1–3.4; p=0.026).

Furthermore, a sensitivity analysis demonstrated that bright light therapy produced greater improvement in the 17-Hamilton Depression Score (group-by-time interaction, p=0.04) for patients who were adherent to therapy.