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Melatonin and sleep latency: grade C

Limited evidence. Direction: Benefit.

C Limited

Educational guidance, not medical advice

Why this grade

Rubric condition met: Pooled estimates mix healthy and clinical (insomnia) populations with no healthy-only estimate; direction not consistent across meta-analyses

A 2005 meta-analysis of 17 studies, 15 in healthy people or people with insomnia only, found melatonin shortened the time to fall asleep by about 4 minutes compared with placebo, and its authors describe the included studies as highly heterogeneous. Meta-analyses in diagnosed sleep disorders report reductions of about 5-7 minutes, and a 2024 dose-response meta-analysis that included healthy volunteers found effects peaking at 4 mg/day. A 2022 meta-analysis found no significant effect in adults with chronic insomnia, and a 2006 meta-analysis found no clear evidence of an effect under sleep restriction, so the direction is not consistent enough for A. No pooled estimate in healthy people alone and no healthy-adult trial in the pack reports sleep onset, and the analyses closest to healthy sleepers (sleep restriction, shift work) found no clear effect on sleep onset, so the grade is C.

How we grade evidence

Studies this grade rests on

EffectMixedNo effectSize shows participants (n)20052010201520202025Meta-analysisMaruani 2023, 2023: meta-analysis, n = 4,875, result not recordedFerracioli-Oda 2013, 2013: meta-analysis, n = 1,683, result not recordedBrzezinski 2005, 2005: meta-analysis, n = 284, result not recordedBuscemi 2006, 2006: meta-analysis, n not recorded, result not recordedChoi 2022, 2022: meta-analysis, n not recorded, result not recordedCruz-Sanabria 2024, 2024: meta-analysis, n not recorded, result not recorded
each study this grade rests on, by publication year and design. Solid: effect versus the comparator; half-filled: mixed; hollow: no effect; dashed: result not recorded yet. Larger marks had more participants.
Show the numbers
StudyYearDesignParticipantsResult
Brzezinski 20052005meta-analysis284result not recorded
Buscemi 20062006meta-analysisnot recordedresult not recorded
Ferracioli-Oda 20132013meta-analysis1683result not recorded
Choi 20222022meta-analysisnot recordedresult not recorded
Maruani 20232023meta-analysis4875result not recorded
Cruz-Sanabria 20242024meta-analysisnot recordedresult not recorded

Efficacy and safety of exogenous melatonin for secondary sleep disorders and sleep disorders accompanying sleep restriction: meta-analysis.

Buscemi N, Vandermeer B, Hooton N. Efficacy and safety of exogenous melatonin for secondary sleep disorders and sleep disorders accompanying sleep restriction: meta-analysis BMJ, 2006. PMID 16473858

Result not recorded
Design
Systematic review and meta-analysis of RCTs (efficacy) and controlled trials (safety)
Population
People with secondary sleep disorders or sleep disorders accompanying sleep restriction (jet lag, shift work)
Funding
PHS HHS 290-02-0023

Efficacy of melatonin and ramelteon for the acute and long-term management of insomnia disorder in adults: A systematic review and meta-analysis.

Maruani J, Reynaud E, Chambe J. Efficacy of melatonin and ramelteon for the acute and long-term management of insomnia disorder in adults: A systematic review and meta-analysis J Sleep Res, 2023. PMID 37434463

Result not recorded
Design
Systematic review and meta-analysis of 22 studies (melatonin and ramelteon)
Sample
n = 4,875
Population
Adults with insomnia disorder (clinical population)
Funding
not stated

Efficacy of melatonin for chronic insomnia: Systematic reviews and meta-analyses.

Choi K, Lee YJ, Park S. Efficacy of melatonin for chronic insomnia: Systematic reviews and meta-analyses Sleep Med Rev, 2022. PMID 36179487

Result not recorded
Design
Systematic reviews and meta-analyses of 24 placebo-controlled RCTs
Population
Patients with chronic insomnia, all ages (clinical population)
Funding
Ministry of Food and Drug Safety, Ministry of Science, ICT and Future Planning, National Research Foundation of Korea

Optimizing the Time and Dose of Melatonin as a Sleep-Promoting Drug: A Systematic Review of Randomized Controlled Trials and Dose-Response Meta-Analysis.

Cruz-Sanabria F, Bruno S, Crippa A. Optimizing the Time and Dose of Melatonin as a Sleep-Promoting Drug: A Systematic Review of Randomized Controlled Trials and Dose-Response Meta-Analysis J Pineal Res, 2024. PMID 38888087

Result not recorded
Design
Systematic review and dose-response meta-analysis of 26 double-blind RCTs
Population
Patients with insomnia and healthy volunteers (1,689 observations)
Funding
Fondazione Arpa, Italian Ministry of Health

Meta-analysis: melatonin for the treatment of primary sleep disorders.

Ferracioli-Oda E, Qawasmi A, Bloch MH. Meta-analysis: melatonin for the treatment of primary sleep disorders PLoS One, 2013. PMID 23691095

Result not recorded
Design
Meta-analysis of 19 randomized placebo-controlled trials
Sample
n = 1,683
Population
Adults and children diagnosed with primary sleep disorders (clinical population)
Funding
Partly funded by APIRE/Eli Lilly Psychiatric Research Fellowship and AACAP/Eli Lilly Pilot Research Award (to author MHB); NIH and non-US government support per PubMed

Effects of exogenous melatonin on sleep: a meta-analysis.

Brzezinski A, Vangel MG, Wurtman RJ. Effects of exogenous melatonin on sleep: a meta-analysis Sleep Med Rev, 2005. PMID 15649737

Result not recorded
Design
Meta-analysis of 17 studies
Sample
n = 284
Population
Mostly healthy subjects or people with insomnia only (15 of 17 studies)
Funding
NCRR NIH HHS 5M01 RR1066-25, National Institutes of Health

Search and history

Search (): melatonin[ti] AND (sleep onset[tiab] OR sleep latency[tiab]) AND (meta-analysis[pt] OR systematic review[pt])

  • Graded B (proposed): Proposed in the monograph draft
  • B to C (proposed): Updated in the monograph draft
  • C to C (approved): Editor sign-off November 13, 2026: grade matches the editor-approved final page