Melatonin supplementation → Sleep duration and regularity
Higher Melatonin supplementation moves Sleep duration and regularity only in some conditions. Read the mechanism.
Luthringer 2009 found that 2 mg of prolonged-release melatonin at night shortened polysomnographic sleep-onset latency by 9 minutes versus placebo in 40 people aged 55 or older with primary insomnia (P=0.02). Baandrup 2017 found no change in sleep efficiency when the same kind of tablet was added during benzodiazepine withdrawal in schizophrenia or bipolar disorder.
Randomized trial · Contested · N=40
Supported by an experiment or a tightly identified design. Read the caveats.
Mechanism
Authors treat a night-time melatonin tablet as a clock cue that might shorten the wait to sleep. Luthringer tests that in older primary insomnia. Baandrup tests it as an add-on while people with severe mental illness come off a benzodiazepine. Luthringer, Muzet, Zisapel and Staner (2009) gave 40 patients aged 55 or older with DSM-IV primary insomnia two single-blind placebo weeks, then three double-blind weeks of 2 mg prolonged-release melatonin or placebo, then three withdrawal weeks. At the end of the double-blind period, sleep-onset latency was 9 minutes shorter on melatonin (P=0.02). Half reported a substantial home-sleep improvement versus 15 percent on placebo (P=0.018). Critical flicker fusion was better on melatonin. Sleep architecture was not harmed. Baandrup, Glenthøj and Jennum (2017) added prolonged-release melatonin or placebo while adults with schizophrenia, schizoaffective disorder, or bipolar disorder tapered long-term benzodiazepines on antipsychotics. One-night polysomnography in 23 people: sleep efficiency did not move. Self-reported sleep quality in 55 people improved. Retention was low.
Caveats
Researchers assigned people to a tablet or a control, so this is a trial stamp. The sign depends on who swallowed it. More papers of the same design do not settle the claim. Luthringer is forty older people with primary insomnia and a Circadin-style 2 mg tablet. Nine minutes on a lab night is the measured change. Baandrup is benzodiazepine withdrawal in schizophrenia or bipolar disorder. Objective efficiency missed. Subjective quality moved. The sample is small and leaky. That context is why the polarity is not a simple positive. This is a journal entry, not medical advice and not a reason to start a night tablet.
Effect
qualitative. Luthringer 2009: PRM 2 mg, N=40, age>=55 primary insomnia. SOL -9 min vs placebo P=0.02. Baandrup 2017: PR melatonin add-on in SMI benzo taper. PSG efficiency NS (N=23). Subjective quality improved (N=55).
Nodes
Named confounders
Cite this page
What Causes What. “Melatonin supplementation → Sleep duration and regularity.” https://whatcauseswhat.org/edges/e-melatonin-sleep (atlas updated 2026-09-02).
Papers
- The effect of prolonged-release melatonin on sleep measures and psychomotor performance in elderly patients with insomnia.
R Luthringer, M Muzet, N Zisapel, L Staner · 2009 · International clinical psychopharmacology
- Objective and subjective sleep quality: Melatonin versus placebo add-on treatment in patients with schizophrenia or bipolar disorder withdrawing from long-term benzodiazepine use.
L Baandrup, BY Glenthøj, PJ Jennum · 2017 · Psychiatry research