This page describes pharmacological agents that may have legal restrictions, side effects, and drug interactions in your jurisdiction. Information is for educational research only — consult a clinician before considering any compound.
Melatonin
Endogenous pineal hormone, OTC supplement — but the dose and timing matter more than the molecule.
Aliases (5)
Overview
What is Melatonin?
Melatonin is the primary circadian hormone secreted by the pineal gland in darkness. As a supplement it is used at low doses for sleep timing and jet lag, and at higher doses for free-radical scavenging.
Key Benefits
Shortens sleep latency at low doses, shifts circadian phase for jet lag and shift work, supports antioxidant defense, and may modulate immune function and inflammation.
Mechanism of Action
Binds MT1 and MT2 G-protein-coupled receptors in the suprachiasmatic nucleus and peripheral tissues to gate the sleep-promoting and circadian-phase-shifting signal. Also acts directly as a potent free-radical scavenger and indirectly upregulates antioxidant enzymes.
Pharmacokinetics
▸Brand options2 known
StatusOTC supplement (US, Canada, much of Asia, LatAm); Rx-only (EU/UK/Australia for adults; pediatric Rx in some jurisdictions); Schedule 4 (Australia in adult Circadin)
Research Indications
MT1 (MTNR1A)
Gi-coupled GPCR, broadly distributed; densest in SCN, hippocampus, hypothalamus. Activation suppresses neuronal firing in the SCN's wake-…
MT2 (MTNR1B)
Gi-coupled GPCR, also broadly distributed; densest in retina, SCN. Activation at the right circadian time shifts the phase of the SCN mas…
MT3 (quinone reductase 2)
Not a true GPCR; an enzymatic binding site involved in detoxification and antioxidant function. Binds melatonin at much higher concentrat…
Nuclear ROR/RZR receptors
Bind melatonin weakly; modulate immune and circadian gene transcription. Probably matters for chronic high-dose pharmacological effects.
Research Protocols
Disclaimer: These are commonly discussed research protocols and not medical advice.
Peptide Interactions
(the user's V stack — 400 mg elemental): Independent mechanisms (NMDA modulation + glycinergic relaxation vs MT1/MT2 signaling). Magnesium has its own modest…
(the user's V stack): CNS-penetrating Mg form; theoretical synergy on NMDA/sleep architecture without melatonin-pathway conflict. Different mechanism, comple…
(the user's V stack planned, replaces glycine): Tryptophan feeds the upstream serotonin → melatonin biosynthesis pathway. Tryptophan at bedtime + low-dose me…
(the user's V stack planned, 50 mg): Mild GABA-A PAM at low doses, plus aromatase inhibition (irrelevant here). Different mechanism; safe co-admin. Apigenin …
(Uvex glasses + outdoor cardio + 10,000-lux box): The other zeitgeber. Morning light advances the clock from the wake side; low-dose evening melatonin advanc…
Not a stack but a co-intervention. Strongly compatible.
as melatonin: substrate-flooding without coordinated phase signal; no benefit, theoretical risk of central serotonin excess at very high combined doses. Diff…
(benzos, Z-drugs, phenibut, GHB, opioids, gabapentinoids, alcohol): additive sedation. Melatonin + a real hypnotic is rarely necessary; the layering is usual…
(CYP1A2 inhibitor): substantially elevates melatonin plasma levels, prolongs duration. Dose adjustment or avoidance needed if both are required. Same caution…
and other coumarin anticoagulants: Possible enhancement of anticoagulant effect (unclear mechanism, possibly via vitamin K modulation or platelet effects). W…
Theoretical concern about additive serotonergic loading via the tryptophan → melatonin pathway and central 5-HT effects, though clinically the interaction si…
Defeats the signal — light suppresses MT2 receptor signaling (and endogenous pineal output). Take the dose in dim light, sit through the dose period in dim l…
Quality Indicators
Tested third-party COA
Reputable brands publish a Certificate of Analysis for identity, potency, and contaminant testing.
GMP-certified manufacturing
Look for cGMP / NSF / USP certifications on the label.
Proprietary blends
Avoid products that hide individual ingredient amounts inside a "proprietary blend."
No origin or sourcing info
Unbranded or no-COA capsules from anonymous sellers carry quality and adulteration risk.
What to Expect
- Week 1Baseline tolerability. Most chronic-use supplements have no acute signal.
- Week 2-4Subtle baseline shift — sleep quality, mood, recovery markers.
- Week 4-8Reach steady state. Re-assess subjective + objective markers.
- Month 3+Long-term maintenance dose if benefit confirmed; otherwise stop.
Side Effects & Safety 7
Side Effects
- 1At physiological doses (0.3-1 mg): essentially placebo-rate side effects.
- 2At higher doses (3-10 mg): vivid / disturbing dreams (~10-20%), morning grogginess (~10-15%), next-day fatigue (~5-10%).
- 3Headache: ~5-7% across doses
- 4Dizziness / lightheadedness: ~3-5%, mostly first week
- 5Nausea / GI upset: rare at low dose, more frequent at supra-doses
- 6Mood changes (irritability, mild dysphoria): occasional, more at chronic high dose
- 7Mid-sleep awakening 4-5 hours after dose: dose-dependent, more frequent at 5+ mg
When to Stop
- Theoretical HPG-axis suppression at supraphysiological chronic dosing — early animal work and a small number of human studies showed melatonin can blunt LH pulsatility / FSH at very high doses (≥75 mg in some research protocols). At standard supplement doses (≤5 mg), human evidence does NOT show clinically significant suppression of testosterone, LH, or FSH in young adult males. For a 20-year-old in this archetype yo on 0.3-0.5 mg low-dose phase-shift protocol, this concern is essentially nil. A theoretical concern that argues against chronic high-dose (5-10 mg gummy) use, NOT against the phase-shift protocol.
- Endogenous melatonin "suppression" concern in young adults — frequently raised on biohacker forums but poorly supported by controlled human data. Endogenous pineal melatonin output does not appear to be downregulated by short-course exogenous melatonin in humans. Adolescent endogenous melatonin levels are higher than adult, falling steeply across teen years — this is normal puberty pharmacology, not a sign that exogenous use damaged it. Real but minor concern at high dose, short course; effectively zero at low dose. Best practice: use the lowest effective dose for the shortest time needed to migrate chronotype.
- Headache, nightmares, persistent next-day sedation — disqualifying for affected individuals; switch to non-pharmacological chronotherapy or try lower dose.
- Allergic reaction: very rare.
- Drug-drug interactions (see Drug interactions): meaningful for fluvoxamine, warfarin, immunosuppressants.
- Hypotension at high doses in some users — rarely clinically significant but worth knowing if the user adds modafinil + creatine training-day cardiovascular load.
- First 2 weeks at any new dose/timing: track morning grogginess, dream content, mid-sleep awakening, daytime mood. If any of these are problematic, drop dose or revisit timing — most issues resolve at 0.3 mg.
- First 6 weeks of phase-advance protocol: track sleep-onset time advance vs target. If no advance after 4-6 weeks of compliant behavioral chronotherapy + low-dose melatonin, reconsider whether problem is circadian or behavioral.
References
Auger et al. 2015 — AASM Clinical Practice Guideline for Treatment of Intrinsic Circadian Rhythm Sleep-Wake Disorders
definitive AASM recommendation for melatonin in DSWPD; foundational guideline document.
View StudyBrzezinski et al. 2005 — Effects of exogenous melatonin on sleep: a meta-analysis (Sleep Med Rev)
the dose-response meta-analysis showing 0.3 mg as effective as higher doses for sleep onset.
View StudyZhdanova et al. 2001 — Melatonin treatment for age-related insomnia (J Clin Endocrinol Metab)
MIT physiological-dose work; 0.3 mg restores physiological melatonin levels in older adults.
View StudyBuscemi et al. 2005 — Efficacy and safety of exogenous melatonin for secondary sleep disorders and sleep disorders accompanying sleep restriction (BMJ)
major meta-analysis; small SOL/TST effects.
View StudyFerracioli-Oda et al. 2013 — Meta-analysis: melatonin for the treatment of primary sleep disorders (PLOS ONE)
19 studies, 1683 subjects; SOL ↓7 min, TST ↑8 min vs placebo.
View StudyMundey et al. 2005 — Phase-dependent treatment of delayed sleep phase syndrome with melatonin (Sleep)
DSWPD-specific phase-advance trial.
View StudySaxvig et al. 2014 — Phase-shifting effects of melatonin in DSWPD (Chronobiol Int)
DSWPD adult RCT.
View Studyvan Geijlswijk et al. 2010 — Dose finding of melatonin for chronic idiopathic childhood sleep onset insomnia (Psychopharmacology)
pediatric DSWPD dose-response.
View Studyvan Maanen et al. 2017 — Melatonin in adolescents with delayed sleep phase syndrome (Sleep)
adolescent DSWPD RCT, directly relevant to young adult use case.
View StudyHerxheimer & Petrie 2002 — Melatonin for the prevention and treatment of jet lag (Cochrane Database)
Cochrane review, jet lag indication.
View StudyLiira et al. 2014 — Pharmacological interventions for sleepiness and sleep disturbances caused by shift work (Cochrane)
shift-work indication.
View StudyLemoine et al. 2007 — Prolonged-release melatonin improves sleep quality and morning alertness in insomnia patients aged 55+ (J Sleep Res)
long-term safety / efficacy in older adults.
View StudyWade et al. 2010 — Efficacy of prolonged-release melatonin in insomnia patients aged 55-80 years (Curr Med Res Opin)
Circadin RCT.
View StudyAndersen et al. 2016 — The safety of melatonin in humans (Clin Drug Investig)
comprehensive safety review.
View StudyGivler et al. 2024 — Chronic melatonin use and long-term safety (Sleep)
2024 long-term safety reassurance with caveats above 24 months / 5 mg.
View StudyCohen et al. 2023 — Quantification of melatonin and serotonin in pediatric melatonin gummies (J Clin Sleep Med)
supplement quality control problem; 88% mislabeled.
View StudyLi et al. 2022 — Trends in use of melatonin supplements among US adults 1999-2018 (JAMA)
increased dose-misuse over time.
View StudyWurtman 2019 — Use of melatonin to promote sleep in older subjects: physiological vs supraphysiological (J Pineal Res)
review of physiological dose rationale.
View StudyHärtter et al. 2003 — Effect of fluvoxamine on melatonin pharmacokinetics (Clin Pharmacol Ther)
CYP1A2 inhibition interaction; AUC ↑17-23×.
View StudyDollins et al. 1994 — Effect of inducing nocturnal serum melatonin concentrations in daytime on sleep, mood, body temperature, and performance (PNAS)
physiological dose effects.
View StudySletten et al. 2018 — Efficacy of melatonin with behavioural sleep-wake scheduling for delayed sleep-wake phase disorder (PLOS Med)
combined melatonin + behavioral chronotherapy RCT.
View StudyBurgess et al. 2010 — Human phase response curves to three days of daily melatonin (J Clin Endocrinol Metab)
Phase Response Curve characterization in humans.
View StudyLewy et al. 1992 — Melatonin shifts human circadian rhythms according to a phase-response curve (Chronobiol Int)
original PRC paper.
View StudyCrowley & Eastman 2018 — Free-running circadian period in humans: tau measurement and clinical implications (Sleep Med Rev)
chronotype mechanism review.
View StudyLeone et al. 1996 — Melatonin versus placebo in the prophylaxis of cluster headache (Cephalalgia)
high-dose cluster headache use.
View StudyMorera-Fumero et al. 2013 — Melatonin and melatonin agonists as treatments for benzodiazepine and hypnotics withdrawal (J Psychopharmacol)
withdrawal context.
View StudySalehi et al. 2019 — Melatonin in medicinal and food plants (Foods)
dietary melatonin context.
View StudyiHerb — Life Extension Melatonin 300 mcg
primary sourcing for the typical protocol for this archetype.
View StudyAASM 2024 update — Behavioral and psychological treatments for chronic insomnia disorder in adults
current guideline reaffirmation.
View StudyCostello et al. 2014 — The effectiveness of melatonin for promoting healthy sleep: a rapid evidence assessment of the literature (Nutr J)
broad evidence assessment.
View StudyBrown et al. 2009 — Light, melatonin and the sleep-wake cycle (J Psychiatry Neurosci)
mechanism review.
View StudyLatest research
- reviewChronic melatonin use and long-term safetyReassures safety up to 24 months at doses ≤5 mg in adults; explicitly flags data gap for very-long-term supraphysiological dosing.
- safety-signalQuantification of melatonin and serotonin in pediatric melatonin gummies88% of 25 melatonin gummy products mislabeled — actual dose ranged 74-347% of label; some contained undisclosed CBD.
- observationalTrends in use of melatonin supplements among US adults 1999-2018Documented increased self-reported melatonin use, often at much higher doses than studied — regulatory/dose-misuse concern.
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