Melatonin is of limited clinical value when used as a short-term treatment for most primary sleep disorders, according to data published in the Journal of General Internal Medicine (December 2005). This hormone has been used increasingly as an alternative pharmacotherapy for a variety of sleep problems.

Although exogenous melatonin appears safe when used for 3 months or less, the analysis of multiple clinical trials suggests that it may be effective only for treating delayed sleep phase syndrome. In patients suffering from this disorder, which involves persistent deviation from the normal sleep pattern, melatonin decreased sleep onset latency to a greater extent than in those with insomnia. This may be a clinically important effect. The authors also identified the need for additional large-scale, controlled studies to assess the use of melatonin for treating sleep problems.