Bright light therapy at midday beneficial for patients with bipolar depression

Reference

Sit DK, McGowan J, Wiltrout C, et al. Adjunctive bright light therapy for bipolar depression: A randomized double-blind placebo-controlled trial. Am J Psychiatry 2018;175(2):131-139.

Synopsis

The authors of this randomized controlled trial enrolled 46 adults aged 18 years to 75 years to assess whether adjunctive treatment with bright light therapy at midday improves remission and depression scores. Patients were included if they had a current episode of depression based on score of at least 20 on the Structured Interview Guide for the Hamilton Depression Rating Scale with Atypical Depression Supplement (SIGH-ADS), and no hypomania or mixed symptoms. Eligible patients received antimanic medication for at least 4 weeks prior to the active study period, and could also receive antidepressants (78%) or sleep aid medications, if applicable. Patients were not eligible if they had a history of manic symptoms within the prior 6 months, rapid cycling within the past year, active suicidal ideation, psychosis, obsessive-compulsive disorder, uncontrolled thyroid disease, substance use disorder within the past 6 months, a positive urine drug screening result, eye diseases, or treatment with photosensitizing drugs. Patients were randomized to receive broad spectrum fluorescent bright light therapy or placebo dim red light therapy. Patients were masked to the kind of light used in the light box provided, and agreed not to search for information about their light box therapy. Light therapy was initiated with a 15-minute session daily between noon and 2:30 PM, increasing by 15 minutes per week to 60 minutes daily by week 4. Titration was conditional on having manageable side effects using the Systematic Assessment for Treatment Emergent Effects scale. Use of the light sources was time-stamped and patients also logged light therapy sessions in a journal. The active treatment group had a higher remission rate of 8 or less on SIGH-ADS, (68% vs 22%; odds ratio 7.5; 95% CI 1.8 - 31.3; P = .003) and a lower mean depression score at the end of the study (9.2 vs 14.9 on SIGH-ADS; P = .03). No hypomania or mood polarity switches occurred. The active treatment group also had higher global functioning (Global Assessment of Function [GAF] score 75 vs 68; P = .03). The study was ended when funding ended, resulting in a smaller-than-planned sample size and wide confidence intervals. It could be questioned whether the statistically significant improvements in the SIGH-ADS and GAF were clinically meaningful.