Quick summary

Melatonin is a supplement commonly used to support sleep and regulate circadian rhythms, with some evidence suggesting support for mood and nervous system health. Current evidence is under active review, and clear official dosage recommendations are not established.

What is it?

Melatonin (N-acetyl-5-methoxytryptamine) is a hormone naturally produced by the pineal gland that helps regulate the sleep-wake cycle. It plays a key role in signaling the body when it’s time to sleep. As a dietary supplement, melatonin is primarily used to support sleep and manage disruptions to circadian rhythms, such as those caused by shift work or jet lag.

How it may work in the body

Melatonin may exert its effects mainly by influencing the regulation of circadian rhythms and modulating pathways related to sleep within the brain.

  • Regulation of circadian rhythm through melatonin receptors located in the brain.
  • Modulation of sleep onset and maintenance via central nervous system pathways.
  • Possible antioxidant and neuroprotective effects that may support nervous system health.

It is important to note that most proposed mechanisms are derived from animal or mechanistic studies, and direct confirmation from human trials about specific biochemical pathways remains limited.

Common supplement forms

  • Immediate-release tablets
  • Extended-release formulations
  • Liquid drops
  • Sublingual tablets

Typical dosage and how it is used

There is no official recommended daily intake or authoritative dosage guideline for melatonin. Dosages used in research studies vary widely depending on the purpose, commonly ranging from 0.3 mg to 10 mg per day for sleep support.

Dosage and timing are important considerations in minimizing side effects and optimizing effects on sleep. It is generally advised to consult with a healthcare provider before using melatonin supplements, especially in special populations such as older adults, pregnant or breastfeeding women.

Natural sources

  • Endogenous production by the pineal gland in humans is the primary natural source.
  • Small amounts are found in some foods, although these are not well quantified and likely contribute minimally to circulating levels.

Absorption and bioavailability

Melatonin taken orally has variable bioavailability due to first-pass metabolism in the liver. The absorption and plasma levels may differ depending on the formulation used:

  • Immediate-release formulations tend to produce rapid peak blood levels.
  • Extended-release formulations provide prolonged, sustained melatonin levels over several hours.

Potential benefits: what does the evidence say?

Sleep support and circadian rhythm regulation

Evidence level: Moderate

Multiple human clinical trials support the use of melatonin for reducing sleep onset latency (the time it takes to fall asleep) and improving sleep quality in specific populations, including shift workers, people experiencing jet lag, and individuals with insomnia. However, study designs, dosing, and measured outcomes vary, and the magnitude of benefits may differ among individuals.

Mood and nervous system health

Evidence level: Limited

Preliminary human studies have investigated melatonin’s potential effects on mood regulation and nervous system support. While some early findings are encouraging, evidence remains insufficient and inconclusive at this time. Further well-designed clinical trials are necessary to establish reliable conclusions.

Side effects and safety

  • Common side effects: Drowsiness, dizziness, headache.
  • Special populations: Pregnant or breastfeeding women should use melatonin with caution due to insufficient safety data. Older adults may experience increased sensitivity to melatonin’s effects.
  • Toxicity and overuse: High doses or inappropriate timing of melatonin intake may lead to next-day drowsiness or potential disruption of the circadian rhythm. Toxicity is considered rare but remains poorly characterized.
  • Quality concerns: Variability in the melatonin content and purity of over-the-counter products has been reported, highlighting the importance of purchasing from reputable brands.

Drug and supplement interactions

Current evidence did not supply detailed information on drug or supplement interactions with melatonin. Given its effects on the nervous system and potential to cause drowsiness, individuals taking sedatives, blood thinners, or other medications should use caution and consult a healthcare provider before use.

Who should be careful?

People who are pregnant, breastfeeding, have medical conditions, use medication, or are planning surgery should consult a healthcare professional before using melatonin. Older adults may also need to start with lower doses due to increased sensitivity.

Pregnancy, breastfeeding and special populations

Safety data for melatonin use during pregnancy and breastfeeding is limited and insufficient. Melatonin supplementation should be used only under medical advice in these groups. Additionally, older adults may require careful dosing consideration because of altered pharmacokinetics and sensitivity.

Quality, standardization and what to look for

Because over-the-counter melatonin supplements can vary considerably in terms of melatonin content and purity, it is advisable to choose products that have been independently tested or certified by reputable third-party quality organizations. Consistent dosing and purity are important to minimize variability in effects and side effects.

Frequently asked questions

  • Is melatonin addictive? Melatonin is not considered addictive, but long-term safety data are limited.
  • Can melatonin help with jet lag? Some evidence supports melatonin use in reducing symptoms of jet lag, although individual responses may vary.
  • What is the best time to take melatonin? Timing is important and usually depends on the purpose (e.g., for sleep onset, melatonin is often taken shortly before bedtime), but specific timing should be discussed with a healthcare provider.
  • Are there natural ways to increase melatonin? Exposure to dim light in the evening and maintaining regular sleep schedules may support the body’s natural melatonin production.
  • Can I take melatonin every night? There is limited evidence on the safety of chronic nightly use; intermittent or short-term use is more common in research settings.

Evidence limitations

  • Many studies vary widely in design, dosage, populations, and measured outcomes.
  • There are no official dosage guidelines established for melatonin supplementation.
  • Safety data for special populations such as pregnant or breastfeeding women are incomplete.
  • Few authorized health claims have been approved by regulatory bodies in the EU or elsewhere.

References

Last reviewed

June 2024

Disclaimer: This page provides an overview of current scientific evidence about melatonin as a dietary supplement. It is not intended to diagnose, treat, cure, or prevent any disease. Always consult a qualified healthcare professional before starting any new supplement regimen, especially if you are pregnant, breastfeeding, have underlying health conditions, or use medications.