Supplements are not tested in clinical trials and are not registered as medications.
Mechanism of action
Melatonin is a pineal hormone that synchronises circadian rhythms with the light cycle. It binds MT1 and MT2 receptors in the suprachiasmatic nucleus of the hypothalamus. Reduces sleep latency and shifts the circadian rhythm when correctly timed. Distinct from classical hypnotics (benzodiazepines, Z-drugs) – does not cause dependence, sedative effect is minimal. Efficacy depends on individual receptor sensitivity and timing relative to the individual circadian rhythm.
Indications
A
Jet lag disorder
First line
Melatonin is first-line for jet lag treatment and prevention. The 2002 Cochrane review (10 RCTs) showed a 50% reduction in jet lag symptoms when crossing 5 or more time zones. Dose: 0.5–5 mg 30 minutes before desired sleep in local time, for 2–5 days after arrival. 2015 recommends melatonin for jet lag with “strong” evidence. Effect is more pronounced with eastward travel.
Doses above 3 mg do not provide additional benefit. In older adults, start at 0.5–1 mg to reduce residual morning sleepiness.
Melatonin in low doses (0.3–0.5 mg) 5–7 hours before desired sleep time is the main pharmacological approach to delayed sleep phase syndrome. 2015 recommends melatonin combined with morning bright-light therapy. Standard hypnotics (Z-drugs, benzodiazepines) do not help in DSPS – the problem is not sleep onset itself but a shifted internal clock. Therapy lasts weeks to months with gradual timing adjustment.
Prolonged-release melatonin (Circadin 2 mg) is -approved for short-term (up to 13 weeks) treatment of chronic insomnia in patients 55 and older. The effect is modest – sleep latency reduction by 9 minutes and improved subjective sleep quality. Used when CBT-I and standard hypnotics are contraindicated. Foundational therapy is CBT-I and sleep hygiene.
The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.
D
Chronic insomnia in adults under 55
Not recommended
2017 recommends against melatonin for chronic insomnia in adults under 55 (weak recommendation, low evidence). Systematic reviews showed a clinically insignificant effect – sleep latency reduction by 4 minutes, sleep duration increase by 13 minutes. Foundational therapy is CBT-I; pharmacological options include doxylamine, short-course benzodiazepine receptor agonists, and orexin antagonists.
Timing is critical. For insomnia and older adults: 30–60 minutes before desired sleep. For DSPS: 5–7 hours before target sleep time. For eastward jet lag: evening local time. For westward: evening local time from day 2–3. Use after midnight in people with normal circadian rhythm shifts the sleep phase and worsens sleep.
Dose titration
Standard supplement dose: 3 mg; pharmaceutical immediate-release: 1.5–3 mg (Melaxen); prolonged-release: 2 mg (Circadin). Optimal dose for most indications: 0.5–3 mg. Doses above 5 mg do not improve sleep onset but increase morning grogginess and nightmare risk. In children with ASD, the dose is individualised in a specialist service.
Monitoring
No specific monitoring is needed with short-term use. With long-term therapy (over 3 months), reassess efficacy and need for continuation. In patients on warfarin, monitor INR when adding melatonin. Individual response varies with baseline endogenous melatonin levels.
Special situations
In children, melatonin is registered in Russia only as Slenyto for children over 2 with autism spectrum disorder. Routine use in healthy children and adolescents is not recommended. In epilepsy, caution is required – seizure threshold reduction has been reported in some patients. In depression, bipolar disorder, or autoimmune disease, use is discussed with the treating clinician.
Common myths
Myth: “melatonin is a safe sleep aid for everyone”. Fact: effect on insomnia in adults under 55 is clinically insignificant. Benefit is established mainly for jet lag and DSPS. In epilepsy, on , or on immunosuppressive therapy, caution is required.
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Children under 2 (all forms); under 18 outside paediatric protocols
Serious adverse effects
Paradoxical reactions – worsening of insomnia, increased anxiety (rare)
Allergic reactions (very rare)
Common adverse effects
Headache
Morning sleepiness
Dizziness
Nausea
Uncommon adverse effects
Vivid dreams, nightmares
Irritability, mood changes
Gastrointestinal discomfort
PregnancyFDA C
Data in pregnancy are insufficient. Endogenous melatonin contributes to pregnancy physiology and foetal development. Supplemental melatonin in pregnancy is not recommended.
Breastfeeding
Transfers into breast milk. Use during breastfeeding is not recommended due to possible effects on infant circadian rhythm.
Frequently asked
What is Melatonin used for?
Melatonin is evaluated for the following indications with varying evidence strength: Jet lag disorder (evidence tier A), Delayed sleep phase syndrome (evidence tier B), Insomnia in older adults (evidence tier B). See the full indication matrix with dosing and citations above on this page.
What are the side effects of Melatonin?
Common side effects of Melatonin (≥ 1 in 100): Headache, Morning sleepiness, Dizziness, Nausea. See the Safety section for uncommon and serious reactions.
Is Melatonin safe during pregnancy?
FDA category C. Data in pregnancy are insufficient. Endogenous melatonin contributes to pregnancy physiology and foetal development. Supplemental melatonin in pregnancy is not recommended.
Is Melatonin compatible with breastfeeding?
Transfers into breast milk. Use during breastfeeding is not recommended due to possible effects on infant circadian rhythm.
Who should not take Melatonin?
Melatonin is contraindicated in: Hypersensitivity to melatonin; Severe hepatic impairment; Autoimmune diseases (relative contraindication); Pregnancy and breastfeeding; Children under 2 (all forms); under 18 outside paediatric protocols. Full list in the Safety section.
“melatonin is a safe sleep aid for everyone”
Melatonin is a hormone of the pineal gland. It is used short-term for sleep disturbances related to jet lag and shift work. In anti-aging and longevity communities, melatonin is taken to slow aging, provide antioxidant protection, and extend life. In healthy adults, no clinical studies of prophylactic anti-aging use exist; international guidelines ( NG219, 2017) do not include melatonin for anti-aging. Long-term high-dose use can cause daytime drowsiness, headache, hypothermia, and effects on reproductive hormones. If melatonin is being taken for longevity, consider seeking a second opinion; for sleep normalization, 1-3 mg an hour before bed in short courses is usually sufficient.
Myth: “higher dose, better effect”. Fact: doses above 3–5 mg do not improve sleep onset but increase morning grogginess and nightmare risk. Supplements at 10 mg and above are marketing, not science.
Myth: “melatonin is the youth hormone”. Fact: antioxidant and anti-ageing effects are not clinically confirmed. Long-term high-dose use in older adults has not been studied. Age-related decline in melatonin secretion is physiological, not pathological.
Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.
effect on insomnia in adults under 55 is clinically insignificant. Benefit is established mainly for jet lag and DSPS. In epilepsy, on warfarin, or on immunosuppressive therapy, caution is required.
“higher dose, better effect”
doses above 3–5 mg do not improve sleep onset but increase morning grogginess and nightmare risk. Supplements at 10 mg and above are marketing, not science.
“melatonin is the youth hormone”
antioxidant and anti-ageing effects are not clinically confirmed. Long-term high-dose use in older adults has not been studied. Age-related decline in melatonin secretion is physiological, not pathological.