Summary: For patients with winter seasonal affective disorder (SAD), 6 weeks of photo-therapy (with a dedicated photo-therapy device) may provide the same improvement in depression scores as 6 weeks of cognitive behavior therapy targeted at SAD (CBT-SAD), at potentially a lower cost (As of January 2016, the retail cost for the photo therapy unit used in this study was ~ $360).

http://www.ncbi.nlm.nih.gov/m/pubmed/25859764/

Strength of Recommendation = B