A scoping review on the use of light therapy in the treatment of moderate to severe depression

Abstract

This scoping review addresses the efficacy of light therapy for moderate to severe depression, a prevalent mental disorder affecting over 264 million people globally. Given the significant side effects associated with pharmacological treatments, such as low efficacy and adherence, non-pharmacological alternatives like light therapy are gaining prominence. Light therapy offers numerous advantages, including low cost, accessibility, and minimal side effects. Despite its promise, a comprehensive scoping review to identify knowledge gaps has been lacking. This review, therefore, aimed to explore the existing evidence on the efficacy of light therapy for moderate to severe depression and to identify methodological limitations within the literature.

A systematic search of databases including Science Direct, Google Scholar, PubMed, Medline, Web of Science, and Scopus was conducted for studies published between 2011 and 2021. The inclusion criteria encompassed cross-sectional, longitudinal, randomized controlled, and cohort designs, while case-control studies and editorials were excluded.

From the initial search, 16 studies were included in the final analysis. The findings indicate that both artificial and natural light therapy are effective in the short and medium term for treating moderate to severe depression, though long-term efficacy was not established. The review identified several methodological gaps, highlighting the need for more longitudinal and long-term cohort studies. Furthermore, it underscored the necessity of considering light therapy as a "complex intervention," standardizing reporting to address inconsistencies, and establishing a consensus on measurement methodologies to reduce heterogeneity.