A critical overview of systematic reviews and meta-analyses of light therapy for non-seasonal depression

Light therapy has increasingly been used in relieving non-seasonal depression. We aimed to summarize the evidence and evaluate the methodological quality regarding the effectiveness and safety of light therapy for non-seasonal depression from systematic reviews/meta-analyses (SRs/MAs). In this study, five databases were searched from their inceptions to January 24, 2022. SRs/MAs on light therapy treatment for non-seasonal depression were included. Methodological quality assessment was performed using the Assessing the Methodological Quality of Systematic Reviews 2 (AMSTAR-2), and evidence quality assessment was performed using the Grades of Recommendation, Assessment, Development, and Evaluation (GRADE). Six SRs/MAs on light therapy treatment for non-seasonal depression were included. The AMSTAR-2 showed that the methodological level of five included SRs/MAs were evaluated as critically low quality, and one included SRs/MAs were rated as low quality. According to the evaluation results of GRADE, the quality of evidence was mostly unsatisfactory. The results and descriptions in the included SRs/MAs suggest that light therapy is effective as a non-pharmacological intervention for the treatment of non-seasonal depression. However, the generally unsatisfied evidence quality and methodological quality of the SRs/Mas indicate that these results must be interpreted with caution.