Melatonin
SupplementThe medical score benefits from a clear EMA approval [s13] and several Cochrane-level meta-analyses [s4, s7], while the community rating is tempered by widespread experiences with excessively high standard dosages and disappointing sleep maintenance effects [c1, c2, c3]. Many users only achieve satisfactory results after dose reduction to 0.3–1 mg, which explains the discrepancy.
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TL;DR
Melatonin is well-supported for sleep onset problems, jet lag, and shift work — the key mistake most users make is taking far too much. Standard commercial doses of 5–10 mg are pharmacologically excessive; physiological doses of 0.3–1 mg are often sufficient for sleep onset and cause significantly less next-day grogginess and vivid dreaming. In Germany, melatonin up to 1 mg is available without prescription; higher doses and extended-release formulations like Circadin® require one. No dependency potential, but it's not a solution for chronic insomnia either.
Description
Endogenous pineal sleep hormone regulating circadian rhythm; effective for sleep onset difficulties, jet lag, and shift work; available without prescription up to 1 mg in Germany [s1, s2].
Melatonin (N-acetyl-5-methoxytryptamine) is an endogenous hormone produced primarily by the pineal gland (epiphysis) in darkness and secreted into the bloodstream [s1]. It is considered the central pacemaker of the human circadian rhythm, regulating the sleep-wake cycle, core body temperature, hormone secretion, and appetite [s2, s3]. Endogenous melatonin production typically begins 1–2 hours before habitual sleep onset (DLMO = Dim Light Melatonin Onset), peaks in the middle of the night, and rapidly declines upon light exposure [s1, s3]. Melatonin production decreases substantially with age, frequently contributing to sleep onset and sleep maintenance difficulties in older adults [s5]. Exogenously administered melatonin at pharmacological doses (0.5–10 mg) mimics the physiological signals of the pineal gland, but may disrupt circadian rhythm when overdosed [s6, s7]. Clinical efficacy is well established for jet lag, delayed sleep phase syndrome, and primary insomnia in older adults [s4, s5, s8]. For general insomnia, meta-analyses demonstrate small to moderate effects on sleep onset latency [s4, s7]. Melatonin possesses additional properties as a potent antioxidant, anti-inflammatory, and potentially neuroprotective molecule [s9, s10], although the clinical relevance of these effects in humans remains largely unclear [s10]. The regulatory situation in Germany is particularly complex: low-dose supplements (≤1 mg) are available without prescription, while higher doses are classified as prescription-only medicinal products [s14]. The BfR explicitly warns against uncontrolled use and highlights unresolved questions regarding long-term safety, particularly in children and adolescents [s6, s12].
Legal Status (DE)
In Germany, melatonin has a two-tier legal status: as a food supplement (NEM), it is marketable without prescription at daily doses up to 1 mg [s14]. The BfArM has classified melatonin as a medicinal product regardless of dose and designated it as prescription-only [s14]. The finished medicinal product Circadin® (2 mg, modified-release) is approved by the EMA for adults aged 55 and over for primary insomnia and is prescription-only in Germany [s13]. Slenyto® is approved for children with autism spectrum disorder and Smith-Magenis syndrome [s13]. The grey area between food supplements and medicinal products results in inconsistent regulatory practice [s14].
Mechanism of Action
Melatonin exerts its primary effects via two G protein-coupled receptors: MT1 (Gi-coupled) and MT2 (Gi/Gq-coupled), which are expressed at particularly high density in the suprachiasmatic nucleus (SCN) of the hypothalamus and in the retina [s1, s3]. MT1 activation inhibits the firing activity of wake-promoting neurons in the SCN and lowers core body temperature — both sleep-preparatory signals [s1, s3]. MT2 activation modulates the phase position of the internal clock and is responsible for the chronobiotic (phase-shifting) effect [s3, s8]. Through this MT2-mediated action, exogenous melatonin can shift the circadian rhythm temporally (phase advance or phase delay), forming the therapeutic basis for jet lag treatment [s8]. Melatonin also inhibits the release of wake-promoting neurotransmitters (e.g., histamine, noradrenaline) and indirectly potentiates GABAergic signaling, contributing to sedation [s1, s3]. As a direct-acting antioxidant, melatonin scavenges reactive oxygen and nitrogen species (ROS/RNS) and activates antioxidant enzymes (e.g., superoxide dismutase, glutathione peroxidase) [s9]. It exerts anti-inflammatory effects via inhibition of the NLRP3 inflammasome and reduction of pro-inflammatory cytokines (TNF-α, IL-6) [s9, s10]. Neuroprotective effects well documented in preclinical studies have so far been only partially confirmed in humans [s10]. Melatonin is metabolized primarily via CYP1A2 (and CYP2C19) in the liver, explaining clinically relevant interactions with CYP1A2 inhibitors (e.g., fluvoxamine: up to 17-fold increase in melatonin levels) and CYP1A2 inducers (e.g., carbamazepine, smoking) [s11, s6].
Dosing
Einschlafprobleme (allgemein)
- Dose
- 0.5–1 mg
- Frequency
- 1× täglich abends
- Route
- oral
- Duration
- kurzfristig (2–4 Wochen), bei Bedarf länger
- Timing
- 30–60 minutes before desired sleep onset
- With food
- optional
Jetlag (Ostreisen)
- Dose
- 3–5 mg
- Frequency
- 1× täglich abends am Zielort
- Route
- oral
- Duration
- 3–5 Tage nach Ankunft
- Timing
- At the desired bedtime at the destination, starting on the day of travel
- With food
- optional
Primäre Insomnie bei älteren Erwachsenen (≥55 J.)
- Dose
- 2 mg (prolonged-release, Circadin®)
- Frequency
- 1× täglich abends
- Route
- oral
- Duration
- 13 Wochen (gemäß Zulassung), Verlängerung ärztlich abklären
- Timing
- 1–2 hours before bedtime
- With food
- optional
Schichtarbeit (Tagschlaf verbessern)
- Dose
- 3–5 mg
- Frequency
- 1× vor dem Tagschlaf
- Route
- oral
- Duration
- bedarfsweise
- Timing
- Shortly before the planned daytime sleep
- With food
- optional
The BfR recommends a maximum daily dose of 1 mg for supplement products [s6]. The American CRN guideline sets the upper limit for dietary supplements at 10 mg/day [s15]. Clinical drug studies have used up to 10 mg; doses >3 mg generally provide no additional benefit for sleep and increase the risk of daytime drowsiness and sleep fragmentation [s7, s4].
Physiological doses (0.3 mg) are often sufficient for sleep onset effects [s7]. Higher doses (5–10 mg) are commonly used for jet lag and shift work but should be medically supervised. Modified-release formulations (e.g., Circadin® 2 mg) are particularly suitable for older patients with sleep maintenance difficulties [s13]. Melatonin should not be taken long-term without medical supervision [s6].
Side Effects
| Side Effect | Frequency | Severity |
|---|---|---|
| Tagesmüdigkeit / Schläfrigkeit am nächsten Morgen Reported particularly at doses ≥3–5 mg; dose-dependent. User reports and clinical data consistent [s4, s7, c1, c2]. | häufig | leicht |
| Lebhafte Träume / Albträume Reported primarily at high doses (≥3 mg); mechanistically explainable by REM modulation [c2, c3]. | gelegentlich | leicht |
| Kopfschmerzen Documented as an occasional side effect in controlled studies [s4, s5]. | gelegentlich | leicht |
| Schwindel / Benommenheit Described in RCT data, particularly at higher doses [s4]. | gelegentlich | leicht |
| Übelkeit Recorded as an occasional side effect in systematic reviews [s4]. | gelegentlich | leicht |
| Störung des zirkadianen Rhythmus bei Fehlzeitnahme When taken at the wrong time (e.g., morning or midday), melatonin can destabilize rather than stabilize the sleep-wake cycle [s6, s3]. | gelegentlich | moderat |
| Erhöhte Prolaktinkonzentration Individual reports of prolactin elevation with possible daytime fatigue and brain fog; systematic clinical evidence limited [c1]. | selten | leicht |
| Hypotonie (Blutdruckabfall) Melatonin can lower nocturnal blood pressure; relevant in pre-existing hypotension [s11]. | selten | leicht |
| Überdosierungsrisiko bei Kindern (Vergiftungsnotfälle) Increasing poisoning emergencies in children due to accidental or intentional overdose of gummy-bear-shaped preparations; BfR and AASM explicitly warn against this [s12]. | selten | schwer |
Contraindications
Reduced CYP1A2 metabolism leads to melatonin accumulation; increased risk of adverse effects. BfR advises against use [s6].
Melatonin has immunomodulatory effects; theoretical risk of worsening autoimmune-mediated inflammatory responses; BfR lists autoimmune diseases as a contraindication for food supplements [s6].
Interaction with antiepileptic CYP1A2 inducers (carbamazepine); BfR advises epilepsy patients against melatonin supplements [s6, s11].
Insufficient safety data available; melatonin crosses the placental barrier and passes into breast milk; use not recommended [s6].
Long-term safety in typically developing children insufficiently established; AASM recommends medical supervision; BfR warns against uncontrolled use [s6, s12].
Interactions
Synergistic
Four-arm RCT (Langade et al. 2025, PMC13108063, n=200) compared KSM-66 300 mg, melatonin 3 mg, combination, and placebo over 8 weeks. The combination showed the strongest effects on sleep parameters. Peer-review status of the publication should be verified before clinical application; classified as preliminary RCT evidence.
No RCT on the direct combination of L-theanine + melatonin found. A meta-analysis (Bulman et al. 2025, 19 RCTs, N=897, s18) demonstrates sleep-improving effects of L-theanine alone (sleep onset latency, sleep quality). A direct comparison of melatonin vs. L-theanine in cancer patients (Kurdi et al. 2024, Indian J Palliat Care) shows melatonin as superior; a combination arm was absent. Synergistic eff...
Magnesium glycinate relaxes muscles and calms the nervous system, while melatonin regulates the sleep-wake cycle. The combination is described as a safe and effective approach for restorative sleep. Both effects complement each other in a complementary manner.
Apigenin exerts anxiolytic and sleep-promoting effects via GABA-A receptors, complementing melatonin in sleep onset. The combination is recommended in established sleep stacks (e.g., Huberman protocol). Both substances act synergistically through distinct mechanisms.
Zinc is an essential cofactor in melatonin biosynthesis from tryptophan. Adequate zinc status supports endogenous melatonin production. The combination may improve sleep quality in cases of zinc deficiency.
B vitamins (particularly B6, B12, folate) are cofactors in melatonin biosynthesis. Adequate supply supports endogenous melatonin production. The combination is especially beneficial in deficiency states.
Glycine lowers core body temperature and improves sleep quality, complementing the sleep-promoting effect of melatonin. Both substances are frequently combined in sleep stacks. The combination is considered safe and complementary.
Both melatonin and alpha-lipoic acid act as antioxidants and may complement each other in protection against oxidative stress. Melatonin is a direct free radical scavenger; alpha-lipoic acid additionally raises glutathione levels. The combination may provide additive antioxidant protection.
Studies
Tier A — High Evidence
Outcome: Optimal dose and timing of melatonin as a sleep aid
Effect Size: Doses 0.3–1 mg effective; higher doses provide no additional benefit; timing is critical
Outcome: Sleep quality (Circadin® 2 mg) in elderly patients with primary insomnia
Effect Size: Significant improvement in sleep quality and morning alertness vs. placebo
Outcome: Efficacy in jet lag, shift work, and circadian rhythm disorders
Effect Size: Clear efficacy evidence for jet lag; moderate evidence for shift work
Outcome: Sleep onset latency, sleep duration, sleep quality in insomnia (comorbid and non-comorbid)
Effect Size: Significant reduction in sleep onset latency; small to moderate effect sizes
Tier B — Moderate Evidence
Outcome: Neuroprotective effects of melatonin in neurodegenerative diseases
Effect Size: Preclinical evidence strong; clinical RCTs limited
Outcome: Antioxidant, anti-inflammatory, and neuroprotective effects of melatonin
Effect Size: Well established preclinically; clinical relevance in humans still unclear
Tier C — Low Evidence
Outcome: Safety and efficacy of melatonin in children and adolescents
Effect Size: Predominantly safe with short-term use; long-term safety insufficiently established
Community Evidence
Top reported benefits
- Faster sleep onset at low doses (0.3–1 mg)
- Very effective for jet lag
- Helps shift workers improve daytime sleep
- Good tolerability at correct dosing
- No dependency potential perceived
Top reported issues
- Daytime fatigue and brain fog at high doses (5–10 mg)
- Vivid or disturbing dreams
- Poor sleep maintenance despite easy sleep onset
- Commercial preparations often overdosed (5–10 mg instead of 0.3–1 mg)
- Does not work in all users (individual variability)
Many users report improved efficacy without side effects only after reducing their dose from 5–10 mg to 0.3–1 mg [c1, c2, c3]. There are isolated reports of possible prolactin elevation with daytime drowsiness following long-term use [c1]. German users report experiences similar to international users; the Meamedica forum indicates that many users find melatonin effective for sleep onset but not for sleep maintenance [c4].
Scientific Sources
- Melatonin - StatPearls
Savage RA, Zafar N, Yohannan S, et al. (2024). NCBI Bookshelf / StatPearlsBPMID:30020613 - Unveiling mysteries of aging: the potential of melatonin in preventing neurodegenerative diseases in older adults
Alghamdi BS, Noor NA, Alamry HM, et al. (2025). Frontiers in Aging Neuroscience / PMCBDOI - Melatonin - Mayo Clinic Drug Information
Mayo Clinic Staff (2024). Mayo ClinicBLink - Melatonin Use in Pediatrics: A Clinical Review on Indications, Multisystem Effects, and Toxicity
Abdelgadir IS, Gordon MA, Bhatt-Mehta V, et al. (2024). Pediatric Emergency Care / PMCBPMID:38518348DOI - Circadin - European Public Assessment Report (EPAR)
European Medicines Agency (EMA) (2007). European Medicines AgencyALink - Melatonin: Rechtslage ungewiss | APOTHEKE ADHOC
Apotheke Adhoc Redaktion (2022). Apotheke AdhocBLink - Recommended Guidelines for Labeling, Formulation, and Packaging of Melatonin-containing Dietary Supplements for Sleep Support
Council for Responsible Nutrition (CRN) (2024). Council for Responsible NutritionALink - Clinical Practice Guideline for the Pharmacologic Treatment of Chronic Insomnia in Adults: An American Academy of Sleep Medicine Clinical Practice Guideline
Sateia MJ, Buysse DJ, Krystal AD, Neubauer DN, Heald JL (2017). Journal of Clinical Sleep MedicineCPMID:27998379DOI - Comparative Evaluation of Ashwagandha (Withania somnifera) Root Extract and Melatonin for Improving Sleep Quality in Adults: A Prospective, Randomized, Double-Blind, Placebo-Controlled Study
Langade D, Thakare V, Kanchi S, Kelgane S [vollständige Autorenliste gemäß PMC-Eintrag] (2025). PMC / Cureus [Preprint / peer-reviewed — Status per Mai 2026 prüfen]CLink - The effects of L-theanine consumption on sleep outcomes: A systematic review and meta-analysis
Bulman A et al. (2025). Sleep Medicine ReviewsCLink - Physiology of the Pineal Gland and Melatonin - Endotext
Arendt J (2022). NCBI Bookshelf / EndotextBLink - The Role of Melatonin in the Circadian Rhythm Sleep-Wake Cycle
Zhdanova IV, Wurtman RJ (2000). Psychiatric TimesBLink - Efficacy of melatonin for chronic insomnia: Systematic reviews and meta-analyses
Fatemeh G, Sajjad M, Niloufar R, et al. (2022). Sleep Medicine ReviewsAPMID:35662582DOI - Melatonin for the Treatment of Insomnia: A 2022 Update
Gamaldo CE, Shaikh AK, McArthur JC (2022). NCBI BookshelfBLink - Melatoninhaltige Nahrungsergänzungsmittel: BfR weist auf mögliche Gesundheitsrisiken hin
Bundesinstitut für Risikobewertung (BfR) (2021). BfRALink - Optimizing the Time and Dose of Melatonin as a Sleep-Promoting Drug: A Systematic Review of Randomized Controlled Trials and Dose-Response Meta-Analysis
Cruz-Sanabria F, Farkas K, Bhatt M, et al. (2024). Journal of Pineal ResearchAPMID:38558464DOI - A Systematic Review and Network Meta-Analysis of Randomized Controlled Trials Evaluating the Evidence Base of Melatonin, Light Exposure, Exercise, and Complementary and Alternative Medicine for Patients with Insomnia Disorder
Cheng P, Luik AI, Fellman-Couture C, et al. (2020). Journal of Sleep Research / PMCAPMID:32374068DOI - Antiinflammatory Activity of Melatonin in Central Nervous System
Cardinali DP, Escames G, Acuña-Castroviejo D (2010). Oxidative Medicine and Cellular Longevity / PMCBPMID:20827338DOI
Community Sources
Storage
Unopened
Store in a cool, dry, light-protected location at room temperature (15–25 °C).
Opened
Keep packaging tightly closed; protect from moisture and direct light.
Notes
Melatonin is light-sensitive; storage in the original container is recommended. For liquid or spray preparations, follow manufacturer instructions.