The efficacy and safety of exogenous melatonin for primary sleep disorders. A meta-analysis

Exogenous melatonin has been increasingly used in the management of sleep disorders.

To conduct a systematic review of the efficacy and safety of exogenous melatonin in the management of primary sleep disorders.

A number of electronic databases were searched. We reviewed the bibliographies of included studies and relevant reviews and conducted hand-searching.

Randomized controlled trials (RCTs) were eligible for the efficacy review, and controlled trials were eligible for the safety review.

One reviewer extracted data, while the other verified data extracted. The Random Effects Model was used to analyze data.

Melatonin decreased sleep onset latency (weighted mean difference [WMD]: -11.7 minutes; 95% confidence interval [CI]: -18.2, -5.2)); it was decreased to a greater extent in people with delayed sleep phase syndrome (WMD: -38.8 minutes; 95% CI: -50.3, -27.3; n=2) compared with people with insomnia (WMD: -7.2 minutes; 95% CI: -12.0, -2.4; n=12). The former result appears to be clinically important. There was no evidence of adverse effects of melatonin.

There is evidence to suggest that melatonin is not effective in treating most primary sleep disorders with short-term use (4 weeks or less); however, additional large-scale RCTs are needed before firm conclusions can be drawn. There is some evidence to suggest that melatonin is effective in treating delayed sleep phase syndrome with short-term use. There is evidence to suggest that melatonin is safe with short-term use (3 months or less).