Shedding Light on SAD: The Effects of Light Therapy in the Treatment of Seasonal Affective Disorder

Abstract

Background: Seasonal Affective Disorder (SAD) consists of recurrent depressive episodes in the fall/winter with summer remission. Symptoms include hypersomnia, fatigue, increased appetite for carbohydrates, and weight gain. The estimated prevalence of SAD is 1.7-2.9% in Canada and is most common in women of reproductive age. Light therapy (LT) is an effective, evidence-based treatment for SAD despite economic and lifestyle burdens. There is a critical need to better understand and evaluate current LT application to determine an optimal treatment strategy for SAD in the future. Objective: To explore the relevant literature regarding the efficacy and physiological and psychological impacts of light therapy in the treatment of Seasonal Affective Disorder among the Canadian adult population. Methodology: Relevant literature was identified using key terms “Seasonal Affective Disorder” and “Phototherapy” or “Light therapy” to search four online databases PubMed, PsychINFO, Web of Science, and Scopus. Results were limited to Canadian publications from 2006 and only included journal articles, clinical trials, meta-analyses, RCTs, and systematic reviews in English. Titles and abstracts were evaluated for relevancy to the objective and inclusion criteria; 7 articles based on Canadian study populations were then subject to analysis. Results: The results were categorized into three themes (efficacy of LT, physiological effects, and psychological effects) and indicated that LT is an effective treatment option for SAD, normalizing physiological SAD symptoms and decreasing SIGH-SAD scores. Conclusions: LT is an effective treatment for SAD with physiological and psychological effects. Further research needs to establish Canadian incidence and morbidity statistics, in addition to indicators/biomarkers for SAD diagnosis and links to symptomatology. Future studies should compare different SAD therapies and develop a standard for efficient LT with long-term and preventative applications as well as optimal compliance.