Melatonin (N-acetyl-5-methoxytryptamine) is a hormone naturally produced by the pineal gland in the brain that plays a central role in regulating the body's circadian rhythm -- the internal 24-hour clock that tells you when to feel sleepy and when to feel alert. Production is triggered by darkness and suppressed by light, which is why melatonin levels typically rise in the evening, peak during the middle of the night, and fall by morning. As a supplement, melatonin is one of the most widely used over-the-counter sleep aids in the world, commonly taken for jet lag, shift work sleep disorder, delayed sleep phase syndrome, and general insomnia.
It is important to understand what melatonin is not: it is not a sedative. Unlike drugs such as benzodiazepines or Z-drugs (zolpidem, zopiclone), melatonin does not force you to sleep or knock you out. Instead, it acts as a "darkness signal" to the brain, gently telling your body that it is time to prepare for sleep. This is why melatonin works best when taken in a dim environment 30-60 minutes before your desired bedtime, and why it is particularly effective for circadian rhythm issues (jet lag, shift work) rather than as a brute-force sleep aid.
One of the most persistent misconceptions about melatonin is dosing. Most OTC melatonin supplements come in doses of 3mg, 5mg, or even 10mg, but research consistently shows that these are far higher than what the body produces naturally. Physiological melatonin levels correspond to roughly 0.1-0.3mg doses. Multiple studies have found that lower doses (0.3-0.5mg) are often more effective for sleep than the megadoses found on pharmacy shelves, because supraphysiological doses can actually desensitize melatonin receptors and cause morning grogginess. The "more is better" approach does not apply to melatonin.
Safety at a Glance
High Risk- Dosing: Less is More
- Create the Right Environment
- Toxicity: Melatonin has an excellent safety profile and is considered one of the safest over-the-counter supplements available....
- Overdose risk: Can You Overdose on Melatonin? A melatonin "overdose" in the traditional sense -- meaning a life-...
If someone is in crisis, call 911 or Poison Control: 1-800-222-1222
Dosage
oral
Duration
oral
Total: 3 hrs – 6 hrsHow It Feels
Most people's experience with melatonin is subtle -- and that is by design. Unlike sedative drugs that produce a distinct "drugged" feeling, melatonin works more like a gentle nudge toward sleepiness rather than a push off a cliff.
Typical effects at standard doses (0.3-1mg): About 30-60 minutes after taking melatonin, most people notice a gradual onset of drowsiness, a sense of relaxation, and a subtle feeling of "heaviness" in the eyelids. It feels similar to the natural wave of sleepiness you experience in the evening -- because it is essentially amplifying the same signal your brain already uses. Many people report that they do not notice a dramatic effect but simply find it easier to fall asleep when they lie down with the lights off.
At higher doses (3-10mg): The drowsiness may be more pronounced, and some people report a heavier, more "sedated" feeling, though this is still far milder than pharmaceutical sedatives. The most commonly reported effect at higher doses isvivid or lucid dreams. Many melatonin users describe their dreams becoming more detailed, narrative, memorable, and occasionally bizarre. This dream enhancement is one of the most consistent subjective effects and is thought to relate to melatonin's influence on REM sleep architecture. Some people enjoy this effect; others find the intense dreams slightly unsettling.
Next-day effects: At appropriate doses, most people feel refreshed the next morning. At doses that are too high (particularly 5mg+), a common complaint is morning grogginess, brain fog, or a "hangover" feeling -- not a true hangover, but a lingering drowsiness that can persist for a few hours after waking. This is usually a sign that the dose was too high rather than an inherent property of melatonin.
What melatonin does NOT feel like: It does not feel intoxicating. There is no euphoria, no altered perception, no "high" of any kind. You will not feel impaired or out of control. It is one of the mildest supplements on the market in terms of subjective experience. People expecting a knockout pill are typically disappointed.
Subjective Effects
The effects listed below are based on the Subjective Effect Index (SEI), an open research literature based on anecdotal reports and personal analyses. They should be viewed with a healthy degree of skepticism. These effects will not necessarily occur in a predictable or reliable manner, although higher doses are more liable to induce the full spectrum of effects.
Physical Effects
Physical(9)
- Decreased libido— Decreased libido is a diminished interest in and desire for sexual activity, commonly caused by subs...
- Dizziness— A sensation of spinning, swaying, or lightheadedness that impairs balance and spatial orientation, o...
- Headache— A painful sensation of pressure, throbbing, or aching in the head that can range from a dull backgro...
- Insomnia— A persistent inability to fall asleep or maintain sleep despite physical tiredness, often characteri...
- Muscle relaxation— The experience of muscles throughout the body losing their rigidity and tension, becoming noticeably...
- Nausea— An uncomfortable sensation of queasiness and stomach discomfort that may or may not lead to vomiting...
- Physical euphoria— An intensely pleasurable bodily sensation that can manifest as waves of warmth, tingling electricity...
- Sedation— A state of deep physical and mental calming that manifests as a progressive desire to remain still, ...
- Seizure— Uncontrolled brain electrical activity causing convulsions and loss of consciousness -- a life-threa...
Cognitive & Perceptual Effects
Cognitive(8)
- Anxiety— Intense feelings of apprehension, worry, and dread that can range from a subtle background unease to...
- Anxiety suppression— A partial to complete suppression of anxiety and general unease, producing a calm, relaxed mental st...
- Depersonalization— A detachment from one's own sense of self, body, or mental processes, as if observing oneself from o...
- Depression— A persistent state of low mood, emotional numbness, hopelessness, and diminished interest or pleasur...
- Dream potentiation— Enhanced dream vividness, complexity, and recall, often occurring as REM rebound after discontinuing...
- Irritability— Irritability is a sustained state of emotional reactivity in which the threshold for annoyance, frus...
- Sleepiness— A progressive onset of drowsiness, heaviness, and the desire to sleep that pulls the individual towa...
- Wakefulness— An increased ability to stay awake and alert without the desire to sleep. Distinct from stimulation ...
Pharmacology
Receptor Pharmacology
Melatonin exerts its sleep-promoting effects primarily through activation of two G-protein-coupled receptors: MT1 (MTNR1A) andMT2 (MTNR1B), which are densely expressed in the suprachiasmatic nucleus (SCN) of the hypothalamus -- the brain's master circadian clock. MT1 receptor activation primarily promotes sleepiness by inhibiting the SCN's wake-promoting signals. MT2 receptor activation plays a larger role in phase-shifting the circadian clock, which is why melatonin is effective for jet lag and delayed sleep phase disorder. Melatonin also binds to the MT3 receptor (now identified as the enzyme quinone reductase 2), though the physiological significance of this binding is less clear.
Beyond its receptor-mediated actions, melatonin is a potent antioxidant that directly scavenges free radicals and stimulates antioxidant enzyme production. It also has immunomodulatory properties and plays a role in regulating body temperature (the slight drop in core temperature that facilitates sleep onset is partly melatonin-mediated).
Pharmacokinetics
Oral melatonin has a bioavailability of approximately 15%, owing to significant first-pass hepatic metabolism. It is rapidly absorbed, with peak plasma concentrations reached within 20-60 minutes depending on the formulation (immediate-release reaches peak faster, extended-release is designed for slower absorption). The plasma half-life is short, approximately 40-60 minutes, which means exogenous melatonin clears relatively quickly -- this is by design, as the body's natural melatonin profile is a gradual rise and fall, not a sustained plateau.
Melatonin is primarily metabolized in the liver by the cytochrome P450 enzyme CYP1A2, which hydroxylates it to 6-hydroxymelatonin. This metabolite is then conjugated (sulfated to 6-sulfatoxymelatonin or glucuronidated) and excreted in urine. Because CYP1A2 is the primary metabolic pathway, substances that inhibit this enzyme (fluvoxamine, ciprofloxacin, caffeine at high doses) can significantly increase melatonin levels, while CYP1A2 inducers (smoking, chargrilled foods) can decrease them.
The Dose-Response Paradox
One of the most interesting pharmacological features of melatonin is its paradoxical dose-response relationship. Unlike most drugs where higher doses produce stronger effects, melatonin often works better at lower doses. Studies by Zhdanova et al. and others have demonstrated that 0.3mg doses produce plasma melatonin levels comparable to natural nighttime peaks and are more effective at promoting sleep than 3mg doses. Higher doses (3-10mg) can cause supraphysiological plasma levels that persist into the morning (causing grogginess), may desensitize MT1/MT2 receptors, and can paradoxically worsen sleep quality in some individuals. This is why many sleep researchers recommend starting at 0.3-0.5mg and increasing only if needed.
Detection Methods
Standard Drug Panel Inclusion
Melatonin is an endogenous neurohormone and widely available dietary supplement that is not detected on any standard drug panel. It is not a controlled substance, has no abuse potential, and is not targeted by any drug testing program. Testing for melatonin is confined to clinical research studying circadian rhythm disorders and sleep physiology.
Urine Detection
Melatonin's primary urinary metabolite is 6-sulphatoxymelatonin (aMT6s), which is routinely measured in clinical research as a non-invasive biomarker of endogenous melatonin production. Exogenous melatonin supplementation elevates aMT6s levels but is indistinguishable from high endogenous production. The metabolite is detectable for approximately 8 to 12 hours after dosing, reflecting melatonin's short half-life (20 to 50 minutes).
Blood and Saliva Detection
Salivary and plasma melatonin levels are routinely measured in clinical sleep research using radioimmunoassay (RIA) or ELISA methods. Dim-light melatonin onset (DLMO) measurement is a standard chronobiology technique. Exogenous supplementation produces supraphysiological levels that are evident on these assays but are not relevant to drug testing.
Hair Follicle Detection
Hair testing for melatonin has no clinical or forensic application. The compound is an endogenous hormone present in all individuals.
Confirmatory Testing
LC-MS/MS can quantify melatonin and 6-sulphatoxymelatonin for research purposes. These methods are highly sensitive and specific but are used exclusively in clinical research settings.
Reagent Testing
Reagent testing is not applicable to melatonin. The compound is available as an over-the-counter supplement and is not subject to adulteration concerns or harm reduction testing.
Interactions
| Substance | Status | Note |
|---|---|---|
| Taurine | Low Risk & Synergy | A popular sleep stack. Taurine improves sleep quality through GABAergic and glycinergic modulation while melatonin regulates circadian rhythm signaling. The mechanisms are complementary and non-overlapping. No known adverse interaction. Many users report better sleep with the combination than with either alone. |
History
Discovery
Melatonin was first isolated and identified in 1958 by Aaron B. Lerner and his colleagues at Yale University School of Medicine. Lerner was a dermatologist investigating the factor in pineal gland extracts that could lighten frog skin pigment (melanocytes). Working with bovine pineal glands obtained from a local slaughterhouse, his team extracted and purified the active compound over a four-year effort that required approximately 250,000 pineal glands. Lerner named the molecule "melatonin" -- combining "mela" from melanin (the skin pigment it affected) with "tonin" from serotonin (the molecule from which it is biosynthetically derived).
Early Research
Throughout the 1960s and 1970s, researchers established melatonin's role as a circadian rhythm regulator. Julius Axelrod and colleagues mapped the neural pathway connecting the eyes to the pineal gland via the suprachiasmatic nucleus, explaining how light controls melatonin production. By the 1980s, the discovery of melatonin receptors in the SCN confirmed its central role in circadian biology. This work laid the groundwork for understanding jet lag, shift work disorder, and the seasonal rhythms that affect mood and reproduction.
Commercial Availability
Melatonin's trajectory as a consumer product is unusual in the history of bioactive compounds:
- 1993-1995: Melatonin supplements first became widely available in the United States. Because melatonin is a naturally occurring hormone (not a synthetic drug), the FDA classified it as a dietary supplement under the Dietary Supplement Health and Education Act (DSHEA) of 1994. This meant it could be sold without prescription and without the rigorous clinical trials required for pharmaceutical drugs.
- The 1990s "melatonin craze": Popular books like "The Melatonin Miracle" (1995) promoted melatonin as a cure for aging, cancer, and virtually everything else, leading to a massive surge in consumer demand. While most of these claims were overblown, the genuine sleep-promoting effects were real.
- International variation: The regulatory status of melatonin varies dramatically worldwide. In the US and Canada, it remains an unregulated OTC supplement. In much of the European Union, Australia, and Japan, it is a prescription medication. The UK reclassified it from prescription-only to pharmacy availability in recent years.
Recent Developments
Usage of melatonin has grown dramatically in the 2020s. A 2022 JAMA study found that melatonin supplement use in the US had increased more than five-fold since 1999, with particular growth during the COVID-19 pandemic (when sleep disruption was widespread). This growth has raised concerns about quality control, appropriate dosing (particularly in children, where gummy melatonin use has surged), and the gap between supplement-industry doses and scientific recommendations.
Harm Reduction
Dosing: Less is More
The single most important harm reduction message for melatonin is that lower doses are usually more effective than higher doses. Start with 0.3-0.5mg (you may need to cut a standard tablet into quarters or find a low-dose formulation). If that does not help after a few nights, gradually increase to 1mg, then 2mg at most. The 5-10mg tablets that dominate pharmacy shelves are dramatically higher than physiological levels and often produce more side effects (morning grogginess, vivid nightmares) without improving sleep quality.
Timing Matters
Take melatonin 30-60 minutes before your desired bedtime, not right as you get into bed. This allows plasma levels to rise and the sleep-promoting signal to reach your brain by the time you want to fall asleep. Taking it too early may cause premature drowsiness; taking it too late means you are lying in bed waiting for it to kick in.
Create the Right Environment
Melatonin works with your body's light-sensitive sleep system, not against it. After taking melatonin:
- Dim the lights in your home
- Avoid bright screens (phones, laptops, TVs) or use blue-light filters / night mode
- Keep your bedroom dark and cool
- Bright light exposure after taking melatonin directly counteracts its effects by suppressing both endogenous and exogenous melatonin signaling
Do Not Drive or Operate Machinery
Even though melatonin is mild, it does cause drowsiness by design. Do not drive, operate heavy equipment, or do anything requiring full alertness after taking melatonin. This is especially important at higher doses where morning grogginess is more likely.
Drug Interactions
Melatonin has some clinically relevant interactions:
- Blood thinners (warfarin, other anticoagulants): Melatonin may increase bleeding risk
- Immunosuppressants: Melatonin has immune-stimulating properties that could theoretically counteract immunosuppressive therapy
- Diabetes medications: Melatonin may affect glucose metabolism and insulin sensitivity
- Birth control pills: Oral contraceptives can increase endogenous melatonin levels, potentially amplifying the effect of supplemental melatonin
- Fluvoxamine: This antidepressant strongly inhibits CYP1A2, dramatically increasing melatonin levels (up to 12-fold). If taking fluvoxamine, use much lower melatonin doses
- Caffeine: Also a CYP1A2 substrate; high caffeine intake close to bedtime can compete with melatonin metabolism
Not a Long-Term Substitute for Sleep Hygiene
Melatonin is best used as a short-term tool for specific situations (jet lag, temporary schedule changes, resetting a disrupted sleep cycle) rather than a permanent nightly crutch. If you need melatonin every night to fall asleep, that is a signal to examine the underlying causes: screen habits, caffeine timing, irregular sleep schedule, stress, sleep environment, or potential sleep disorders that should be evaluated by a doctor.
Toxicity & Safety
Melatonin has an excellent safety profile and is considered one of the safest over-the-counter supplements available. No lethal dose has been established in humans, and even very large doses (up to 100mg+ in research settings) have not produced life-threatening toxicity.
Common Side Effects
Most side effects are mild, transient, and dose-dependent:
- Next-day drowsiness or grogginess -- the most common complaint, usually indicating the dose was too high
- Headache -- mild, typically resolves on its own
- Dizziness -- uncommon, more likely at higher doses
- Nausea -- occasional, mild
- Irritability -- rarely reported, more common in children
Long-Term Considerations
While short-term melatonin use is well-established as safe, long-term daily use (months to years) has some theoretical concerns that are still being studied:
- Reproductive hormones: Some studies have suggested that sustained high-dose melatonin supplementation may affect reproductive hormone levels (suppressing GnRH and downstream hormones like LH and FSH). This is primarily a concern at supraphysiological doses and is more relevant to adolescents and those trying to conceive. At physiological doses (0.3-0.5mg), this effect appears negligible.
- Possible dopamine interaction: High-dose melatonin may modestly inhibit dopamine release in certain brain regions, though the clinical significance of this is unclear and it has not been associated with depressive symptoms in studies.
- Circadian disruption: Poorly timed melatonin use (e.g., taking it at inconsistent times or in the morning) could theoretically worsen circadian rhythm issues rather than help them.
- Supplement quality: Because melatonin is sold as a dietary supplement in the US (not regulated as a drug), actual melatonin content can vary dramatically from label claims. A 2017 study in the Journal of Clinical Sleep Medicine found that melatonin content ranged from -83% to +478% of the labeled dose, and 26% of supplements contained serotonin as a contaminant. Buying from reputable brands with third-party testing is advisable.
Dependence and Withdrawal
Melatonin is not habit-forming and does not cause physical dependence. There is no withdrawal syndrome upon discontinuation. Some people report temporary difficulty falling asleep after stopping melatonin, but this appears to be a return to baseline rather than a rebound or withdrawal effect. Tolerance to melatonin's sleep-promoting effects has not been clearly demonstrated in studies.
Special Populations
Melatonin should be used with caution in:
- Children: While generally considered safe for short-term use, long-term effects on development (particularly puberty) are not fully characterized. Pediatrician guidance is recommended.
- Pregnant and breastfeeding individuals: Insufficient data to confirm safety. Melatonin crosses the placenta and is present in breast milk.
- People with autoimmune conditions: Due to melatonin's immunomodulatory effects, caution is warranted.
- People with seizure disorders: Some evidence suggests melatonin may lower seizure threshold in susceptible individuals, though other studies suggest neuroprotective effects. Medical guidance is recommended.
Addiction Potential
Melatonin is not habit-forming and has no abuse potential. It does not activate reward pathways, does not produce euphoria, and does not cause physical dependence or withdrawal symptoms upon discontinuation. Tolerance to its sleep-promoting effects has not been demonstrated in clinical studies. It is one of the few sleep aids with essentially zero risk of dependence.
Overdose Information
Can You Overdose on Melatonin?
A melatonin "overdose" in the traditional sense -- meaning a life-threatening toxic dose -- is essentially not possible with commercially available supplements. There are no documented cases of fatal melatonin overdose in the medical literature. Even in research settings where volunteers have been given doses of 100mg or more, no serious toxicity has occurred.
What Happens at Very High Doses
Taking too much melatonin (for example, accidentally taking 20-30mg+ instead of 1-3mg, or a child getting into a bottle of gummy melatonin) can cause:
- Excessive drowsiness that may persist well into the next day
- Headache, sometimes significant
- Nausea and possible vomiting
- Dizziness and disorientation
- Irritability, particularly in children
- Diarrhea (uncommon)
- Blood pressure fluctuations (melatonin can affect blood pressure in both directions depending on the individual)
- Vivid nightmares or very disturbing dreams
What to Do
For an adult who has taken a large but non-extreme dose of melatonin (e.g., 10-50mg by mistake): there is generally no need for emergency medical treatment. They should be allowed to sleep in a safe position and monitored for comfort. Symptoms will resolve on their own as melatonin is rapidly metabolized (half-life ~60 minutes).
For children who have ingested a large amount of melatonin: contact Poison Control (1-800-222-1222 in the US) or your local emergency number. While serious toxicity is unlikely, children are more sensitive, doses relative to body weight are higher, and some melatonin supplements contain other active ingredients (such as serotonin contaminants, herbal blends, or vitamins) that may pose additional risks.
Seek medical attention if the person experiences:
- Severe persistent vomiting
- Significant blood pressure changes (feeling faint, racing heart)
- Confusion or disorientation lasting more than a few hours
- Difficulty breathing (extremely unlikely from melatonin alone but warrants evaluation)
- Seizure (very rare; more likely if melatonin is combined with other substances)
Tolerance
| Full | after prolonged and repeated usage |
| Half | 7 days |
| Zero | 14 days |
Cross-tolerances
Legal Status
Australia: Melatonin is schedule 4 (prescription only) except when included in schedule 3 (pharmacist only) for human use:
in modified release tablets containing 2 mg or less of melatonin for monotherapy for the short term treatment of primary insomnia characterised by poor quality of sleep for adults aged 55 or over, in packs containing not more than 30 tablets.
Canada: Melatonin is freely available to purchase as a dietary supplement and can be found at most pharmacies and grocery stores across the country.
France: Melatonin is available over the counter
Germany: Melatonin is a prescription medicine, according to Anlage 1 AMVV. It is however available as a dietary supplement in certain forms, often in low dosages or as combination preparations.
India: Melatonin is legal to purchase as a dietary supplement.
Italy: Melatonin is legal to purchase as a dietary supplement.
Ireland: Melatonin is a prescription-only medicine.
Sweden: Melatonin is an over-the-counter medication in small amounts, but generally a prescription pharmaceutical.
Switzerland: Melatonin is listed as a "Abgabekategorie B" pharmaceutical, which generally requires a prescription.
United Kingdom: Melatonin is a licensed prescription-only medicine (POM) in the United Kingdom. It is not a criminal offense to possess this medicine without a valid prescription. This medicine can legally be obtained with a valid prescription or through legal import of the medicine for personal use as outlined in Section 13 of the Medicines Act 1968.
United States: Melatonin is listed as an uncontrolled substance and is legal to possess and distribute, and is freely available to purchase as a dietary supplement.
Responsible use
Oneirogen
Neurotransmitter
Hormone
Tryptamine
Melatonin (Wikipedia)
Melatonin as a medication and supplement (Wikipedia)
Melatonin (Erowid Vault)
Melatonin (TiHKAL / Isomer Design)
Melatonin (DrugBank)
Melatonin (Drugs.com)
Melatonin (Examine)
Tips (6)
Lower doses of melatonin (0.3-0.5mg) are often more effective than the 5-10mg pills commonly sold in stores. Research shows that supraphysiological doses can actually worsen sleep quality and cause morning grogginess. Try cutting a 1mg tablet in half or look for low-dose formulations.
Take melatonin 30-60 minutes before your desired bedtime, not right when you get into bed. It takes time for plasma levels to rise and the drowsiness signal to reach your brain. Dim the lights after taking it -- bright light directly counteracts melatonin's effects.
Melatonin is not a sedative -- it will not knock you out. It works by signaling to your brain that it is time to sleep. If you take it and then stare at your phone under bright lights, do not be surprised when it does not work.
Vivid and sometimes strange dreams are one of the most common effects of melatonin, especially at higher doses. If the dreams are too intense or disturbing, try reducing your dose. Many people find the sweet spot is below 1mg.
Melatonin is best used as a short-term tool for jet lag, schedule changes, or resetting a disrupted sleep cycle -- not as a permanent nightly sleep crutch. If you cannot sleep without melatonin every night, talk to a doctor about the underlying cause rather than relying on supplementation indefinitely.
Store melatonin supplements away from light and heat, as the molecule degrades with exposure. The supplement industry is poorly regulated -- actual melatonin content can vary dramatically from label claims. Buy from reputable brands with third-party testing (look for USP, NSF, or ConsumerLab verification).
Community Discussions (10)
See Also
References (3)
- PubChem: Melatonin
PubChem compound page for Melatonin (CID: 896)
pubchem - Melatonin - TripSit Factsheet
TripSit factsheet for Melatonin
tripsit - Melatonin - Wikipedia
Wikipedia article on Melatonin
wikipedia