Circadian Time of Morning Light Administration and Therapeutic Response in Winter Depression

Abstract

THE FIRST controlled clinical trial of bright light treatment for seasonal affective disorder (SAD)¹ demonstrated a therapeutic effect with daily exposures in the morning and evening. Since then there have been numerous studies indicating an advantage of morning over evening light exposure in cross-center pooling of data² and a Cochrane meta-analysis.³ Recently, 3 large clinical trials have further established a benefit over nonphotic placebo controls,⁴ the superiority of morning light over evening light exposure,⁵ or both.⁶