Serfaty MA, Osborne D, Buszewicz MJ, et al. A randomized double-blind placebo-controlled trial of treatment as usual plus exogenous slow-release melatonin (6 mg) or placebo for sleep disturbance and depressed mood. Int Clin Psychopharmacol. 2010 May;25(3):132-42

This randomized, controlled trial studied whether melatonin promotes sleep and reduces depression. Thirty-three participants with major depressive disorder and early-morning waking were given either slow-release melatonin (6 mg) or placebo at bedtime over 4 weeks. A trend towards improvement in mood with melatonin was found. No adverse side effects were seen. Melatonin may be beneficial for treating major depressive disorder given its high tolerance and low safety concern, but its potential for treating depression requires further evaluation.