The effect of bright light therapy on major depressive disorder: A systematic review and meta-analysis of randomised controlled trials

The increasing prevalence of major depressive disorder (MDD) has led to increased demand for psychotherapy and pharmacotherapy, yet concerns were raised regarding the cost and accessibility to these therapies. Bright light therapy (BLT) has shown promise in mitigating depressive symptoms of non-seasonal affective disorders. This meta-analysis gathered evidence from randomised controlled trials (RCTs) to assess the effectiveness of BLT on patients with non-seasonal MDD. Five databases were systematically searched. The primary outcome of the meta-analysis was the endpoint depression score from the BLT and control treatment groups, with the remission and response rates as the secondary outcomes. Results are presented in standardised mean difference (SMD) and log odd ratio. Subgroup analyses compared the effects of trial length and the length of daily exposure. Results on 15 RCTs between 1996 and 2024 with 883 patients showed positive effects of BLT on alleviating depressive symptoms (SMD = 0.48, 95 % CI [0.22, 0.74], p