Circadian realignment and depressed mood: A systematic review.

Chronotherapeutic interventions aimed at realigning the circadian system can improve depression. This systematic review evaluated the current evidence for circadian realignment as an antidepressant mechanism. A comprehensive search was conducted in studies that implemented a chronotherapeutic intervention in samples with depression and/or delayed sleep/circadian timing using PubMed, EMBASE, Cochrane Central Register of Controlled Trials (Wiley), Europe PMC, and PsycINFO. The Downs and Black checklist was used to evaluate study quality. There were 58 studies included, of which 23 studies reported the association between realignment and depression. Circadian realignment was associated with improved depression in studies that included participants with baseline delays and elevated depression. Randomized clinical trials measuring circadian phase markers are needed to further elucidate circadian realignment as an antidepressant mechanism.