Melatonin: Benefits, Dosage, and Safety

What melatonin is

Melatonin is a hormone (N-acetyl-5-methoxytryptamine) produced mainly by the pineal gland in the brain in response to darkness; the body synthesizes it from serotonin. As a dietary supplement it is usually made synthetically, though it can be derived from animals or microorganisms. It is not an essential nutrient, so no Dietary Reference Intake (RDA, AI, or UL) has been established for it. In the United States it is regulated as a dietary supplement, not a drug.

What it does

• Helps time the body's circadian rhythms, the roughly 24-hour internal clock
• Signals darkness and helps promote the onset of sleep
• Is produced by the pineal gland in response to darkness; light exposure at night can suppress its production
• Research suggests it may play additional roles in the body beyond sleep, though these are not fully understood

Intake and dosing

Melatonin is not an essential nutrient, so no Recommended Dietary Allowance or Tolerable Upper Intake Level has been set. Doses in studies vary widely. Because supplement doses are not standardised, discuss an appropriate amount with a clinician or pharmacist.

Deficiency and who is at risk

Melatonin is not a dietary nutrient, so there is no classical deficiency state or deficiency disease. Endogenous production can be lower with older age, with nighttime light exposure, and in some medical conditions, and reduced levels are commonly seen in people with insomnia, but this is not a nutritional deficiency and is not routinely diagnosed or treated as one.

Who may need more

• Travelers with jet lag crossing multiple time zones
• People with delayed sleep-wake phase disorder (DSWPD), under guidance
• Some children with sleep problems linked to conditions such as ASD or ADHD, only with a health care provider's supervision
• Adults with anxiety before surgery, in clinical settings
• Anyone considering it should first talk with a health care provider, especially children, pregnant or breastfeeding women, and people on medicines

Food sources

Melatonin is not obtained in meaningful amounts from a normal diet and is not a required food nutrient. Trace amounts occur naturally in some foods (for example certain fruits, grains, and other plant foods), but food is not a practical or standardized source, and dietary intake is not tracked for health purposes.

Forms and absorption

Available over the counter as tablets, capsules, liquids, and flavored gummies, in both immediate-release and prolonged- or controlled-release formulations. Most supplement melatonin is made synthetically. Product quality is inconsistent: testing has found actual melatonin content ranging from far below to far above the label amount, and some products have contained serotonin as a contaminant. Prescription melatonin-receptor agonist drugs (ramelteon, tasimelteon) are separate FDA-approved medicines and are not the same as melatonin supplements.

Safety, excess and interactions

Too much

Melatonin has low acute toxicity, and no lethal dose has been established in animal studies even at very high doses. Reported effects at higher supplement doses and with extended-release forms include drowsiness, daytime sedation, headache, dizziness, and nausea. Because melatonin is a hormone, excess intake could in theory affect hormonal processes. Over-the-counter products are frequently mislabeled: a 2023 study found 22 of 25 melatonin gummy products were inaccurately labeled, with melatonin ranging from 74 to 347 percent of the stated amount, so users may unknowingly take much more than intended. Unsupervised pediatric ingestion is a growing safety concern: U.S. poison-control reports for people under 20 rose from 8,337 in 2012 to 52,563 in 2021, and a CDC report estimated about 11,000 emergency-department visits from 2019 to 2022 for unsupervised ingestion by children 5 and younger.

Interactions to know

• Anticoagulant and antiplatelet (blood-thinning) medicines: people taking blood thinners should use melatonin only under medical supervision because of a possible increased bleeding risk (for example with warfarin)
• Anticonvulsant (antiseizure) medicines: people with epilepsy should be under medical supervision, as melatonin may affect seizure control
• Sedatives and hypnotics (for example benzodiazepines, zolpidem, eszopiclone) and alcohol: combining with melatonin may cause excessive sedation or drowsiness
• CYP1A2 inhibitors such as fluvoxamine: can raise melatonin blood levels because melatonin is metabolized by CYP1A2; estrogens and quinolone antibiotics may also increase melatonin levels
• Immunosuppressant therapy and autoimmune conditions: caution is advised because melatonin may stimulate immune activity
• General: people taking any medicine, and those with medical conditions or scheduled for surgery, should consult a health care provider before using melatonin

How status is measured

Not routinely measured. Melatonin status is not part of standard clinical care and has no established target level. In research settings, endogenous melatonin is assessed through blood, saliva, or urine measurements (for example the dim-light melatonin onset, DLMO), but these are specialized tools used to study circadian timing rather than routine tests to check a person's melatonin level.

In the United States, melatonin is regulated by the FDA as a dietary supplement, not as a prescription or over-the-counter drug, so it is subject to less strict regulation and is not FDA-approved to diagnose, treat, cure, or prevent any disease. Product content is not tightly controlled, and testing has repeatedly found mislabeled amounts. In several other countries melatonin is available only by prescription and is treated as a drug. (Separately, the melatonin-receptor agonist drugs ramelteon and tasimelteon are FDA-approved prescription medicines and are distinct from melatonin supplements.)

What the evidence supports

We grade the strength of evidence behind each common reason people take melatonin, mirroring how the NIH describes it.