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

Abstract

Depression is a common mental disorder affecting more than 264 million people worldwide. Although depression is a severe mental disorder, pharmacological treatments have many side effects, such as low efficacy and adherence. Therefore, there has been an increasing awareness about the importance of non-pharmacological treatments. Light therapy has many advantages: low cost, availability and accessibility anywhere, acceptability, feasibility, and minimal side effects. Although light therapy is a promising intervention for depression, there is a lack of scoping reviews. This can be beneficial as it can identify the potential gaps in the literature. Therefore, this scoping review sought to explore the scope of evidence on the efficacy of light therapy for moderate to severe depression. It also aimed to identify potential methodological limitations in the available literature. Several databases were searched, such as Science Direct, Google Scholar, Scopus, PubMed, MedLine, Web of Science, and Scopus. Studies between 2011 and 2021 were included. Studies with a cross-sectional design, longitudinal design, randomised controlled design, and cohort design were included, whereas studies with case-control design and editorials were excluded. The final list included 16 studies. It was found that artificial light therapy is an effective treatment for moderate to severe depression in both the medium and short term, but not the long term. Also, it was found that natural light therapy has similar efficacy in treating moderate to severe depression. The review found that light therapy can be effective for different grades of depression (moderate and severe depression). Several methodological gaps were identified, such as the need for longitudinal design and long follow-up cohort design studies. The review also found that there is a need to take the concept of complex interventions” into consideration. It is also essential to standardise reporting as there was inconsistency in reporting of studies. There is a need for a consensus on the methods that should be used as there was a great extent of heterogeneity in the measures used.