Melatonin: Sleep Hormone Science, Safe Dosage & What Research Really Shows

What Is Melatonin?

Melatonin (N-acetyl-5-methoxytryptamine) is a hormone produced primarily by the pineal gland in the brain. The pineal gland is located deep in the centre of the brain, approximately the size of a pea. Melatonin is also produced in smaller amounts in other tissues, such as the gastrointestinal tract.

Melatonin is essentially the chemical signal of darkness: when it becomes dark, melatonin levels rise; when light reaches the retina, production is suppressed. This makes melatonin a key regulator of the circadian rhythm — the body's internal 24-hour clock.

The precursor of melatonin is serotonin, which is derived from the amino acid tryptophan. In the pineal gland, serotonin is converted into melatonin through light-dependent enzymes.

How Does Melatonin Work? — Mechanism and Receptors

Melatonin acts through specific receptor proteins, primarily MT1 and MT2, located throughout the body including the suprachiasmatic nucleus (SCN) of the hypothalamus — the body's central timekeeper.

Typically, the pineal gland begins producing melatonin around 9 pm. Levels rise, peak between 2 and 4 am, and fall again by early morning. In parallel, cortisol levels drop in the evening and rise in the morning — an opposing rhythm that promotes waking.

Melatonin also has antioxidant properties that have been studied in laboratory settings. However, these properties do not constitute EFSA-authorised health claims for melatonin dietary supplements.

Light and Circadian Control

Bright light in the evening — particularly short-wave blue light from screens — suppresses melatonin production and can delay the time it takes to fall asleep. In low-light winter conditions, daytime suppression of melatonin production may be incomplete, contributing to daytime fatigue. This forms part of the basis of seasonal mood variations, which should be medically assessed if persistent.

EFSA-Authorised Health Claims for Melatonin

Following scientific review, EFSA has authorised two health claims for melatonin. Only these may be used confidently in the promotion of dietary supplements:

Melatonin as a Dietary Supplement

In Germany, Austria and Switzerland, melatonin is available as a dietary supplement — typically at doses of 0.5 mg to 1.9 mg per daily dose. Higher dosages are common in other markets (e.g. the USA), but this does not indicate that higher doses are necessary or safer.

Melatonin is not classified as a medicine as long as it stays within recommended dosages and no medicinal claims are made. For sleep disturbances beyond occasional difficulty falling asleep, medical evaluation is recommended.

Natural Ways to Optimise Melatonin Levels

Alongside supplementation, these lifestyle measures can support natural melatonin production:

• Maintain regular sleep and wake times — including at weekends
• Reduce evening blue light exposure from screens (from approximately 2 hours before bedtime)
• Darken the bedroom — light exposure inhibits melatonin production
• Get adequate natural daylight during the day — this regulates the circadian rhythm
• Reduce caffeine, alcohol and nicotine — all can affect melatonin levels
• Regular physical activity during the day supports healthy sleep-wake patterns

Melatonin and Sleep in Older Adults

Several studies suggest that melatonin production declines with age, which may contribute to commonly observed changes in sleep quality in older people. Some supplementation studies show positive effects on sleep onset time in this group. However, older adults should consult a doctor before taking melatonin, as interactions with other medications are possible.

Melatonin and Jet Lag

Melatonin is the best-studied dietary supplement for jet lag. The EFSA-authorised claim confirms that at least 0.5 mg melatonin, taken shortly before bedtime at the destination over several days, can alleviate subjective jet lag symptoms including fatigue, difficulty concentrating and disturbed sleep after transmeridian flights.

Antioxidant Properties — Current Research Status

Laboratory and animal studies have investigated antioxidant properties of melatonin, including the ability to neutralise free radicals and influence mitochondrial function. These findings are scientifically interesting but do not constitute EFSA-authorised health claims for dietary supplements.

Ongoing Research — Preliminary Findings Without Approved Claims

Cardiovascular System

Some studies have examined whether melatonin may influence blood pressure. Results are inconsistent and insufficient for a definitive assessment. Melatonin does not replace antihypertensive medication.

Gastrointestinal Health

Melatonin is also produced in the gastrointestinal tract. Animal studies and some human studies have investigated gastroprotective effects. No therapeutic conclusions for humans can currently be drawn from this research.

Eye Health

Due to its antioxidant properties, melatonin has been investigated in relation to intraocular pressure and retinal health. This is at an early research stage; no approved claims exist.

Neurodegenerative Conditions — Early-Stage Research

Smaller observational studies and laboratory experiments have investigated melatonin in relation to neurodegenerative processes relevant to conditions such as Parkinson's and Alzheimer's disease. These studies are exploratory and do not allow conclusions about prevention or treatment. Patients and caregivers should work exclusively with specialist medical professionals.

Sleep and Mental Health

Sleep disturbances are a common accompanying symptom in various mental health conditions. Some studies have examined whether melatonin can contribute to sleep improvement in these groups. This research is conducted under clinical supervision. Melatonin supplements do not replace psychiatric or psychotherapeutic treatment. Always consult a specialist for mental health conditions.

Tinnitus

Individual small studies have investigated the effect of melatonin on subjective tinnitus. The evidence is limited. Patients with tinnitus should consult an ear, nose and throat specialist.

Fibromyalgia and Pain Perception

Some pilot studies have investigated melatonin in relation to pain perception in fibromyalgia patients. Evidence is based on very small studies; robust clinical data are lacking. Fibromyalgia requires specialist medical care.

Cancer Research

Dosage Guidelines — General Information

According to EFSA, 1 mg melatonin taken shortly before bedtime is the recommended dose for reducing sleep onset time. For jet lag, at least 0.5 mg is recommended. EU dietary supplements are typically available at up to approximately 1.9 mg per daily dose.

• Start with the lowest effective dose (0.5–1 mg)
• Take melatonin 30–60 minutes before intended sleep time
• Avoid higher doses without medical advice
• Long-term use should be medically supervised
• Combinations with alcohol, sleep medications or other substances: consult doctor or pharmacist

Melatonin and Children

In clinical research, melatonin is studied under strict medical supervision in children with specific neurodevelopmental conditions (e.g. ADHD, autism spectrum disorder). This is not transferable to over-the-counter dietary supplements.

Side Effects of Melatonin

Melatonin is generally considered well-tolerated for short-term use at low doses. Possible side effects in sensitive individuals include:

• Daytime sleepiness or grogginess (especially with too high a dose or incorrect timing)
• Headache
• Dizziness
• Nausea

If side effects persist, discontinue use and consult a doctor.

Melatonin Interactions

Melatonin may interact with various medications. Consult a doctor or pharmacist before use, particularly with:

• Blood thinners (e.g. warfarin)
• Diabetes medications
• Blood pressure medications
• Immunosuppressants
• Antiepileptics
• Sleeping aids and sedatives
• Antidepressants

Is Melatonin Safe?

At recommended doses and for short-term use, melatonin is considered safe for healthy adults. Groups requiring special caution:

• Pregnant and breastfeeding women: Insufficient safety data; supplementation not advised
• Children and adolescents: Only under medical supervision
• Persons with autoimmune conditions: Medical consultation required
• Persons with liver or kidney conditions: Consult doctor
• Patients with mental health conditions: Only under psychiatric supervision

Melatonin During Menopause

Sleep disturbances are common during menopause and may be related to hormonal changes. Some studies have examined the effect of melatonin on sleep in perimenopausal women. Results are not yet definitive. Women experiencing menopause-related sleep difficulties should discuss all options with their gynaecologist.

References

For scientific transparency, key sources are listed below.

• European Food Safety Authority (EFSA): Authorised EU health claims for melatonin — EU Register No. 432/2012
• Ferracioli-Oda E et al. (2013). Meta-Analysis: Melatonin for the Treatment of Primary Sleep Disorders. PLOS ONE. https://pubmed.ncbi.nlm.nih.gov/23691095/
• Herxheimer A, Petrie KJ (2002). Melatonin for the prevention and treatment of jet lag. Cochrane Database of Systematic Reviews. https://pubmed.ncbi.nlm.nih.gov/12076414/
• Hardeland R (2012). Melatonin in aging and disease. Interdisciplinary Topics in Gerontology. https://pmc.ncbi.nlm.nih.gov/articles/PMC3377831/
• BfR (Bundesinstitut für Risikobewertung): Safety assessment of melatonin in food supplements.