Digestery
Everyday supplements › Melatonin and Sleep › Studies

Pooled review (meta-analysis)

Pooled review of 26 studies: melatonin sped falling asleep and lengthened sleep

Cruz-Sanabria and colleagues · Journal of pineal research · 2024

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

Under review. A person has not yet checked this summary against the paper. It is written from the PubMed abstract. Until a person checks it, search engines are asked not to list this page.

What the study found

Points to benefit

Melatonin gradually reduced time to fall asleep and raised total sleep time, peaking at 4 mg/day. Taking it 3 h before bedtime may work better than 2 mg 30 min before.

The study at a glance

Type of study
Pooled review (meta-analysis)
Who or what was studied
26 studies · people with insomnia and healthy volunteers
What was tested
Melatonin vs placebo at different doses and times; effect on time to fall asleep and total sleep time
What it measured
The question itself: sleep, and safety with long-term use
Daily amount
4 mg a day
Who has a stake
No disclosure in PubMed
No disclosure in PubMed; funded by Fondazione Arpa and Italian Ministry of Health.
Journal
Journal of pineal research, 2024
Source
PubMed record 38888087. This page is based on the abstract only.

How much this study counts

  • ✓Pools the results of 26 studies.
  • •A pooled review is only as strong as the studies it pools.
  • ✓Measured the question itself: sleep, and safety with long-term use.
  • •The PubMed record has no conflict-of-interest statement.
  • •Summarized from the PubMed abstract only. The full paper may hold details the abstract leaves out.

✓ Strength– Limit• Note

These points come from fixed rules about the type of study, its size and length, what it measured, and who has a stake. Every study on Digestery gets the same rules.

Where this study sits

This paper is not on the ladder. It is a pooled review (meta-analysis), and reviews and opinion pieces discuss studies that are already counted on the steps below.

↑ Stronger evidence

  1. Trials in people: sleep onset and sleep quality

    8

    2 benefit, 2 mixed, 4 no difference

  2. Trials in people: other measures

    2

    1 benefit, 1 no difference

  3. Trials in people: lab tests or safety

    0

    None among the papers we read.

  4. Population studies

    0

    None among the papers we read.

  5. Blood levels and genes

    0

    None among the papers we read.

↓ Weaker evidence

  • Points to benefit
  • Mixed
  • No difference
  • No direction
  • Points to harm

How it fits with the other research

The short answer to “Does melatonin help you sleep?”

A small effect, clearer in children.

Confidence: low. Based on 20 on-topic papers.

Read the full answer
  • Part of the finding “Falling asleep: a few minutes faster”.
  • Summed up in “What reviews found”: Pooled 26 placebo trials (1689 observations) in people with insomnia and healthy volunteers. The effect on falling asleep and total sleep grew with dose, peaking at 4 mg/day, and with earlier timing.
  • Marked as a key paper in the research timeline: Dose review: effect peaks at 4 mg/day.

Other reviews on this question

See all 20 studies on this question

How this page was made

Label

First read of the abstract
Claude Sonnet
Independent second read
Claude Haiku
Differences settled
The two reads agreed on every checked field. Claude Opus 5.5.
Headline
Claude Sonnet, from the checked study record. A script checked its numbers and wording.
Numbers
Checked against the abstract by a script
“How much this study counts”
Fixed rules, the same for every study
Source check by a person
Not yet. Required before search engines may list this page.

Spot an error? Email a flag with a link to your source, or use the form on the question page.