Clinical Question: Is melatonin effective for insomnia and other sleep problems?

Setting: Outpatient (any)

Study Design: Meta-analysis (randomized controlled trials)

Synopsis: The authors of this systematic review evaluated the role of melatonin in the treatment of various sleep problems in a variety of patients. The authors performed a thorough search of the literature, although they limited the research to English-language publications. Potential research was screened by two independent reviewers and data were abstracted by one reviewer and checked for accuracy by another. Controlled clinical trials were included and all studies were reviewed for quality using the established Jadad criteria.

In patients with normal sleep patterns, melatonin had a clinically insignificant effect on the time to sleep onset (i.e., sleep onset latency) or on the amount of time actually spent asleep (i.e., sleep efficiency). Melatonin in doses of 1 to 3 mg caused an average delay of 12.7 minutes in the onset of rapid eye movement (i.e., REM latency) compared with placebo.

In patients with simple insomnia, melatonin helped adults fall asleep an average of 10.7 minutes faster (95 percent confidence interval [CI], 3.7 to 17.6 minutes). Children had a better response, falling asleep an average of 17 minutes sooner. Melatonin was particularly effective in patients with delayed sleep phase syndrome, a condition in which a person’s circadian rhythm is misaligned without an external cause such as jet lag or shift work. In these patients, sleep onset was an average of 38.8 minutes faster (95 percent CI, 27.3 to 50.3 minutes). Melatonin had no effect on sleep quality, wakefulness, total sleep time, or percentage of time spent in REM sleep.

In patients with jet lag, melatonin did not decrease sleep onset latency or increase sleep efficiency, sleep quality, or the time spent in REM sleep, although it was effective in increasing the total sleep time. In one study, melatonin had an effect similar to zolpidem (Ambien) in patients with jet lag. Melatonin was not effective in patients with a secondary sleep disorder.

Bottom Line: Melatonin in doses from 0.1 to 10 mg is effective in helping adults and children who have difficulty falling asleep. It is particularly helpful in patients whose circadian rhythm is permanently disrupted (i.e., those who have delayed sleep phase syndrome). Melatonin increases sleep length, but not sleep quality, in patients who perform shift work or who have jet lag. (Level of Evidence: 1a)