Condition
    Moderate Evidence
    Effectiveness 3/5

    Melatonin for Poor Sleep Quality

    Melatonin shortens sleep onset modestly in poor sleepers and works considerably better when the underlying problem is circadian timing rather than sleep quality itself. Low doses outperform high ones.

    Overview

    Melatonin is a timing signal rather than a sedative, and that distinction explains most of the disappointment people report. It tells the body that biological night has begun. When poor sleep comes from a clock that is running late or from travel across time zones, that signal is exactly what is missing and melatonin helps reliably. When poor sleep comes from stress, pain, alcohol, apnoea or a racing mind at 3am, melatonin has little to offer, because none of those are timing problems. Meta-analyses find a modest average benefit: sleep onset shortens by roughly seven to twelve minutes and total sleep time increases slightly. Real, worth having, but not a knockout drug.

    Verdict

    Likely effective

    Multiple meta-analyses show melatonin modestly shortens time to fall asleep and improves sleep quality, with larger effects in circadian problems such as delayed sleep phase and jet lag than in general insomnia.

    How It Works

    Melatonin is released by the pineal gland once light stops reaching the suprachiasmatic nucleus, and it acts on MT1 and MT2 receptors there. MT1 activity dampens the wake-promoting drive of the clock; MT2 activity shifts the phase of the clock itself. This is why timing matters more than dose: taken in the early evening it advances the clock, taken in the early morning it delays it. Because the effect is a signal rather than sedation, large doses do not produce proportionally better sleep. They do produce higher daytime levels, which blur the contrast between biological day and night and can leave people groggy — the common complaint that usually means the dose is too high, not too low.

    Pathways involved

    MT1 receptor suppression of wake drive
    MT2 receptor circadian phase shifting
    Suprachiasmatic nucleus signalling
    Core body temperature decline
    Light-mediated melatonin suppression

    Dosing & Protocol

    Physiological doses of 0.5 to 1 mg reproduce natural night-time levels and are what dose-finding work supports. Commercial products commonly supply 5 to 10 mg, which is well above what the receptors need and is the usual reason for morning grogginess and vivid dreams. Timing carries most of the effect. For simply falling asleep, take it 30 to 60 minutes before bed. For shifting a late body clock, take a small dose four to six hours before your current sleep onset and pair it with bright light on waking. Prolonged-release formulations were studied specifically in adults over 55, where endogenous melatonin declines, and improved sleep quality and next-day alertness in that group.
    GoalDoseFormTiming
    Falling asleep faster0.5-1 mgImmediate release30-60 min before bed
    Delayed sleep phase0.5 mgImmediate release4-6 hours before current sleep onset
    Jet lag (eastward)0.5-3 mgImmediate releaseLocal bedtime, first 3-5 nights
    Adults over 552 mgProlonged release1-2 hours before bed
    1. 1

      Rule out the non-timing causes· Before starting

      Snoring with daytime sleepiness, alcohol, untreated pain, late caffeine and shift patterns need addressing first; melatonin will not overcome them.

    2. 2

      Start at 0.5-1 mg· Nights 1-7

      Begin low. If you wake groggy, halve the dose rather than raising it.

    3. 3

      Keep the timing constant· Ongoing

      Same clock time each night, since the effect is a phase signal and inconsistent timing cancels it out.

    4. 4

      Control light· Daily

      Dim light for the hour before bed and bright light within 30 minutes of waking. Light does more phase-shifting work than the tablet does.

    5. 5

      Review at 2-4 weeks· Week 4

      If sleep onset has not improved, the problem is probably not circadian. Stop and reassess rather than escalating the dose.

    Evidence

    Two meta-analyses in the mid-2000s set the baseline: in primary sleep disorders melatonin reduced sleep onset latency by around four to twelve minutes and produced small improvements in sleep efficiency, with a parallel analysis of secondary sleep disorders finding a similar modest benefit. Later syntheses of primary adult sleep disorders reached the same conclusion with better methodology, and consistently reported that effects are largest in delayed sleep phase disorder. Dose-finding work in childhood sleep onset insomnia found that timing predicted the response better than dose did, reinforcing the signal rather than sedative model. A separate randomised trial of prolonged-release melatonin in adults aged 55 to 80 found improved sleep quality and next-day alertness without withdrawal effects, which is the strongest indication-specific evidence in the set.
    Best available evidence
    Several meta-analyses and randomised placebo-controlled trials
    Typical effect
    Sleep onset shortened by roughly 7-12 minutes; small gains in sleep quality
    Studied dose
    0.5-5 mg immediate release; 2 mg prolonged release in over-55s
    Time to effect
    First night for jet lag; 1-2 weeks for circadian shifting
    Certainty of evidence
    Moderate; effects consistent but small, with heterogeneous trial quality

    Meta-analyses of melatonin for primary and secondary sleep disorders, a dose-finding randomised trial, and a randomised trial of prolonged-release melatonin in adults aged 55-80.

    Efficacy of prolonged release melatonin in insomnia patients aged 55-80 years: quality of sleep and next-day alertness outcomes

    Score: 7/10
    2007
    rct
    n=170

    Wade AG, Ford I, Crawford G +4 more

    Prolonged-release melatonin significantly improved sleep quality and morning alertness versus placebo, with no rebound insomnia.

    View source

    Melatonin for sleep disorders

    Score: 8/10
    2013
    meta_analysis
    n=1683

    Ferracioli-Oda, E., Qawasmi, A.

    Melatonin reduced sleep onset latency and increased total sleep time and sleep quality across primary sleep disorders.

    View source

    Evidence for the efficacy of melatonin in the treatment of primary adult sleep disorders

    Score: 9/10
    2017
    systematic_review

    Auld F, Maschauer EL, Morrison I +2 more

    Melatonin showed the strongest evidence for reducing sleep onset latency in primary insomnia and for circadian rhythm disorders.

    View source

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

    Score: 9/10
    2006
    meta_analysis

    Buscemi N, Vandermeer B, Hooton N +6 more

    Melatonin did not produce a clinically meaningful reduction in sleep onset latency in secondary sleep disorders or sleep restriction.

    View source

    The efficacy and safety of exogenous melatonin for primary sleep disorders: a meta-analysis

    Score: 9/10
    2005
    meta_analysis

    Buscemi N, Vandermeer B, Hooton N +6 more

    Melatonin reduced sleep onset latency by a small but statistically significant amount, with no significant effect on sleep efficiency or total sleep time.

    View source

    Dose finding of melatonin for chronic idiopathic childhood sleep onset insomnia: an RCT

    Score: 8/10
    2010
    rct
    n=72

    van Geijlswijk IM, van der Heijden KB, Egberts ACG +2 more

    All melatonin doses advanced sleep onset and dim light melatonin onset compared with placebo, with no dose-response relationship.

    View source

    Safety

    Short-term safety is good. The commonest complaints are morning grogginess, headache, vivid dreams and mild dizziness, and grogginess in particular usually reflects an unnecessarily high dose. Trials of prolonged-release melatonin found no rebound insomnia or withdrawal on stopping, which distinguishes it from sedative hypnotics. Two practical cautions matter. Product quality varies widely, with independent testing repeatedly finding actual content well off the label claim, so third-party tested products are worth insisting on. And melatonin is not established as safe in pregnancy or breastfeeding, and long-term use in children should be supervised because of theoretical effects on pubertal timing.

    When melatonin is the wrong tool

    Loud snoring with witnessed pauses, early morning waking with low mood, or insomnia lasting over three months all need proper assessment. Cognitive behavioural therapy for insomnia outperforms melatonin for chronic insomnia and is the recommended first-line treatment.

    Interactions & Conflicts

    Interacts withSeverityMechanismAction
    Warfarin and other anticoagulants
    moderate
    		Possible additive effect on bleeding riskDiscuss with prescriber before use
    Fluvoxamine
    high
    		Strong CYP1A2 inhibition raises melatonin levels several-foldAvoid the combination or use a much smaller dose under advice
    Sedatives, benzodiazepines and alcohol
    moderate
    		Additive sedation and next-day impairmentAvoid combining; do not drive if drowsy
    Antihypertensives (beta-blockers)
    low
    		Beta-blockers suppress endogenous melatonin; blood pressure effects may be alteredMonitor blood pressure if using regularly
    Diabetes medication
    low
    		Melatonin may modestly affect overnight glucose handlingMonitor glucose when starting
    Immunosuppressants
    moderate
    		Melatonin has immune-modulating activityAvoid without specialist advice

    References

    1. Auld F et al. Evidence for the efficacy of melatonin in the treatment of primary adult sleep disorders. Sleep Med Rev. 2017
    2. Buscemi N et al. The efficacy and safety of exogenous melatonin for primary sleep disorders: a meta-analysis. J Gen Intern Med. 2005
    3. Wade AG et al. Efficacy of prolonged release melatonin in insomnia patients aged 55-80 years. Curr Med Res Opin. 2007

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