Effects of Low Oral Doses of Melatonin on Sleep in Normal Young Humans

Aug 31, 2026

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Low oral doses of melatonin increase circulating melatonin concentrations to nocturnal levels and promote polysomnographically measured sleep onset without changing mood or next-morning performance. A study of 12 healthy young volunteers, free of sleep disturbances, compared 0.3 mg or 1.0 mg melatonin with placebo taken 2–4 hours before habitual bedtime. Melatonin significantly reduced sleep-onset latency and latency to stage 2 sleep, while sleep architecture remained unchanged and no hangover effects emerged.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages9

Reading Time23 min

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Summary

Effects on sleep onset and latency

Sleep architecture and hangover effects

Study background and rationale

Methods

Despite general awareness of the unique character-istics of the pineal gland,particularly its rhythmic,photically entrainable secretion of melatonin at night(1-3),no function has been definitively associated inhumans with either the pineal gland or its hormone,melatonin.Candidates for such a function include par-ticipation in the regulation of circadian rhythms(4,5),humoral communication of information about environ-mental lighting (and thus time of day)to the brain andother organs(6),regulation of reproductive physiology (7)and induction of sleep(8,9). The concurrence of the release of melatonin fromthe pineal gland and the time during which most hu-mans sleep(3)has led to a long-standing but unprovedsuspicion that the former process is causally related tothe latter(10).Desynchronization of these two dailyrhythms,behavioral rhythm of sleep time and rhythmic # Effects of Low Oral Doses of Melatonin,Given 2-4 Hours Before Habitual Bedtime,On Sleep in Normal Young Humans Irina V.Zhdanova,Richard J.Wurtman,Claudia Morabito,Veronika R.Piotrovska and Harry J.Lynch Clinical Research Center and Department of Brain and Cognitive Sciences,Massachusetts Institute of Technology,Cambridge,Massachusetts,U.S.A. Summary:Low oral doses of melatonin raise serum melatonin concentrations to those normally occurring noc-turnally and facilitate polysomnographically assessed sleep onset when given at different time points throughoutthe day,without altering mood or performance on the morning following treatment.In the present study,12 younghealthy volunteers,free of sleep disturbances,received 0.3 or 1.0 mg of melatonin or placebo at 2100 hours,2-4hours prior to their habitual bedtime.Polysomnographic recording of overnight sleep began at 2200 hours andcontinued until 0700 hours the following morning,when subjects were awakened.Sleep onset latency and latencyto stage 2 sleep were significantly decreased as a result of melatonin treatment.Neither dose of melatonin signifi-cantly altered sleep architecture.Administration of the lower dose of melatonin(0.3 mg)at 2100 hours elevatedserum melatonin to levels within the normal nocturnal range(113±13.5 pg/ml)at the time the sleep test wasinitiated.Neither melatonin dose caused “hangover effects”,as assessed by self-reports or by mood and performancetests administered on the morning following treatment.These observations provide additional evidence that noc-turnal melatonin secretion has a sleep-promoting function.They also indicate that an increase in serum melatoninconcentrations,within the normal physiologic range,does not significantly alter sleep architecture in subjects withnormal sleep who receive the treatment several hours prior to their habitual bedtime.Key Words:Melatonin—Pineal gland—Polysomnography—Sleep. melatonin secretion,can occur as a result of:1)com-plete blindness,when the melatonin rhythm free-runs,with a period usually longer than 24 hours;2)pine-alectomy or functional destruction of the pineal gland,resulting in a lack of melatonin production;or 3)tem-poral displacement of the daylight period,as in shift-work or transmeridian flight (the jet-lag syndrome).Such disruptions in the coordination of sleep and mel-atonin secretion were correlated with subjects'com-plaints of reduced sleep quantity and quality.The ame-lioration of such subjectively assessed sleep distur-bances by timely administration of pharmacologicaldoses of melatonin(11-13)was attributed to the in-volvement of melatonin in coordinating day-night be-havioral rhythmicity.Timing of the evening augmen-tation in melatonin secretion or the onset of the urinary6-sulfatoxymelatonin excretion has also been shown tocorrelate with the nocturnal increase in sleep propen-sity(14-16).These observations supported the idea oftemporal association of the sleep process and nocturnalmelatonin secretion,although they could not provecausal dependency between these two daily rhythms. EFFECTS OF LOW DOSES OF MELATONIN ON SLEEP

FAQs

What was the main purpose of the study?

To characterize how elevated circulating melatonin levels within the normal nocturnal range affect polysomnographic parameters of overnight sleep in young healthy volunteers with normal sleep quality.

When and how were melatonin doses administered?

Participants received 0.3 mg or 1.0 mg melatonin, or placebo, at 21:00, 2–4 hours before their habitual bedtime.

Did melatonin alter sleep architecture or cause hangover effects?

Neither melatonin dose significantly altered sleep architecture, and no hangover effects were detected based on self-reports and next-morning mood and performance tests.

Aug 31, 2026

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