PND9 - The Efficacy of Melatonin for primary insomnia: a systematic Review and meta-analysis

Abstract

We performed a systematic review of randomized controlled trials (RCTs) to estimate the efficacy of melatonin versus placebo or other hypnotic agents on the improvement of sleep quality and quantity in patients with primary insomnia. We searched the published literatures in eight electronic databases, including Ovid-Medline, EMBASE, the Cochrane Library, and five Korean databases through October 2014. We included articles comparing efficacy for sleep between melatonin and placebo or other hypnotics among primary insomnia patients. The quality of studies was evaluated by using the Cochrane’s risk of bias. The mean difference (MD) or standardized mean difference (SMD) was calculated using the random-effects method for each study outcome. To assess heterogeneity of inter-trial, we used the I2-statistic. Subgroup-analyses were performed by assessment tools, study designs, ages and dosage of melatonin. Funnel plots were used to assess publication bias. Eighteen RCTs were identified and the comparison groups of all included trials were placebo. Compared with placebo, melatonin significantly reduced sleep onset latency (MD: -6.58 min [95% confidential interval (CI): -9.75 to -3.41], p < 0.0001), and increased total sleep time (MD: 20.56 min [95% CI: 4.70 to 36.41], p = 0.01) and sleep efficiency (MD: 3.47% [95% CI: 0.37 to 6.58], p = 0.03). Sleep quality was also improved (SMD: 0.22 [95% CI: 0.03 to 0.40], p = 0.02) in melatonin group but this result was concluded based on a small number of studies. In subgroup-analyses for each outcome, there was no clinically remarkable finding. We did not find any evidence of statistical heterogeneity and publication bias. Melatonin showed to be effective for sleep in comparison with placebo, thus can be an effective option for the treatment of insomnia. Further studies are needed to conclude safety profiles, economic usefulness and tolerance of melatonin.