Meta-analysis: melatonin for the treatment of primary sleep disorders.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of randomized placebo-controlled trials
PubMed 23691095 · doi:10.1371/journal.pone.0063773
What was done
A systematic review and meta-analysis of randomized, placebo-controlled trials searched via PubMed evaluated the efficacy of melatonin in children and adults with primary sleep disorders. Primary outcomes were sleep latency, total sleep time, and sleep quality. Meta-regression evaluated the impact of trial duration and melatonin dosage.
What was found
Across 19 randomized controlled trials with 1,683 participants, melatonin significantly improved sleep outcomes compared to placebo: - Sleep latency decreased by a weighted mean difference (WMD) of 7.06 minutes (95% CI 4.37 to 9.75; p < 0.001). - Total sleep time increased by a WMD of 8.25 minutes (95% CI 1.74 to 14.75; p = 0.013). - Sleep quality showed a standardized mean difference improvement of 0.22 (95% CI 0.12 to 0.32; p < 0.001). Meta-regression found that higher doses and longer trial durations were associated with greater reductions in sleep latency and increases in total sleep time, but did not significantly modify effects on sleep quality.
Why it matters
Melatonin provides statistically significant, durable improvements in sleep onset and duration with a favorable side-effect profile, though the absolute magnitude of improvement is modest compared to prescription hypnotics.
Limits
The search reported in the abstract was limited to a single database (PubMed). The absolute clinical effect sizes were small (~7 minutes faster sleep onset and ~8 minutes longer total sleep). The analysis pooled diverse pediatric and adult populations, and specific adverse effect rates or individual trial quality metrics were not detailed in the abstract.
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- supports Clinical studies show supplemental melatonin improves sleep latency but does not reliably sustain sleep throughout the night.