This randomized, double-blind, placebo-controlled study evaluated the efficacy of bright light therapy as an add-on treatment for adults with bipolar I or bipolar II disorder experiencing a mild-to-moderate depressive episode. The study examined whether bright light therapy improves depressive symptoms and also evaluated its effects on clinical status, psychosocial functioning, sleep quality, circadian characteristics, and treatment-emergent adverse effects.
Participants continued their existing mood stabilizer and/or atypical antipsychotic treatment at unchanged doses and were randomly assigned to receive either active bright light therapy (10,000 lux) or placebo light therapy (1,500 lux). Both groups used the same light therapy device at home for 30 minutes daily between 12:00 PM and 2:00 PM for four weeks. Clinical assessments were conducted before treatment and weekly throughout the four-week treatment period. The primary outcome was remission at the end of week 4, defined as the Structured Interview Guide for the Hamilton Depression Rating Scale-Seasonal Affective Disorder Version total score below 9.
