Meta-Analysis of the Efficacy of Melatonin for the Treatment of Primary Sleep Disorders

This study aimed to evaluate the efficacy of exogenous melatonin compared to a placebo in treating primary sleep disorders. While melatonin is widely used, the researchers sought to synthesize data from randomized, placebo-controlled trials to determine its impact on sleep latency (time taken to fall asleep), total sleep time, and overall sleep quality.

The authors conducted a meta-analysis of 19 randomized, placebo-controlled trials involving 1,683 participants. They utilized statistical methods, including weighted mean differences (WMD) and standardized mean differences (SMD), to aggregate results across studies. Additionally, the researchers performed meta-regressions to investigate whether the dosage of melatonin or the duration of treatment influenced the observed outcomes, while also checking for publication bias and heterogeneity between the studies.

The meta-analysis found that melatonin provides a statistically significant, albeit modest, benefit for patients with primary sleep disorders:

• Sleep Latency: Melatonin reduced the time to fall asleep by an average of approximately 7 minutes.
• Total Sleep Time: Melatonin increased total sleep duration by an average of about 8 minutes.
• Sleep Quality: Subjects reported a significant improvement in overall sleep quality compared to those taking a placebo.

The study also noted that longer treatment durations and higher doses were associated with greater improvements in sleep latency and total sleep time, suggesting that patients do not develop a tolerance to melatonin over time.

While prescription sleep medications (such as benzodiazepines) generally show stronger effects on sleep latency than melatonin, they often carry risks of dependency, habituation, and significant side effects. This study highlights that melatonin is a viable, safer alternative for managing primary sleep disorders. Given its benign side-effect profile and lack of evidence for tolerance, melatonin remains a valuable tool in clinical practice for patients seeking to improve their sleep without the risks associated with stronger pharmacological agents.