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Melatonin

Melatonin is a hormone secreted in the brain that regulates sleep. It appears to be highly sensitive to Light Therapy and Dark Therapy. Oral ingestion of melatonin may be used as a sleep aid. It is non-addictive.

Our evidence-based analysis on melatonin features 387 unique references to scientific papers.

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Summary of Melatonin

Primary information, health benefits, side effects, usage, and other important details

Melatonin is a neurohormone secreted by the pineal gland in the brain and it is well known for causing and regulating sleep. Light suppresses melatonin synthesis. The primary use of melatonin as a supplement is to normalize abnormal sleep patterns.

Melatonin for sleep

Irregular sleep patterns are associated with a wide variety of health problems and premature aging. Melatonin is the hormone used by your body to help you fall asleep, and thus supplementation is seen as a way to get regular sleep. This is particularly useful for people who engage in shift work or are jet lagged.

Other benefits of melatonin include general neuroprotective effects, as melatonin is a powerful antioxidant. Melatonin also has several anti-cancer properties, and is currently being investigated for its role in fighting breast cancer. It does not appear to have much of an effect on lean mass or body fat, but it potentially stops your body from gaining more fat. Melatonin supplementation also benefits eye health, possibly reduces tinnitus, and improve mood (by helping you get better sleep).

Melatonin’s primary mechanism is by helping decrease the time it takes to fall asleep (as a hormone, that's its primary job).

There are some demographics that tend to have irregular melatonin production in their body. Smokers tend to be less responsive to supplementation, and older people tend to not produce as much during night time. Depression has also been associated with lower melatonin levels.

Any side effects to melatonin?

Taking melatonin is not associated with negative feedback (when taking supplementation causes your body to produce less of a hormone). It is also not addictive, and is not toxic.

Want the unbiased truth about melatonin?

We've created a fact sheet that neatly summarizes the scientific research on melatonin.

How to Take

Medical Disclaimer

Recommended dosage, active amounts, other details

For regulating the sleep cycle, doses of melatonin between 500mcg (0.5mg) and 5mg seem to work. Start with 500mcg, and if it doesn’t work, work up to 3-5mg. The benefits of melatonin are not dose-dependent - taking more will not help you fall asleep faster.

To help with sleep, take roughly 30 minutes before going to bed.

Growth hormone appears to spike slightly better at 5mg than 500mcg, although both doses are fairly effective.

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Human Effect Matrix

The Human Effect Matrix looks at human studies (it excludes animal and in vitro studies) to tell you what effects melatonin has on your body, and how strong these effects are.
Grade Level of Evidence
Robust research conducted with repeated double-blind clinical trials
Multiple studies where at least two are double-blind and placebo controlled
Single double-blind study or multiple cohort studies
Uncontrolled or observational studies only
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Outcome Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
Notes
grade-b Strong Very High See all 4 studies
Melatonin is the reference drug for insomnia related purposes, and appears to be highly effective at 3mg (time release formulation) or lower concentrations when taken before sleep.
grade-b Strong Very High See all 6 studies
Plasma melatonin is increased at both night and daylight following supplementation of melatonin. Although the degree of increase is a tad unreliable, it seems to always occur and to a fairly large magnitude
grade-b Notable High See all 4 studies
There appears to be an increase in serum gastrin levels following ingestion of melatonin in persons with stomach ulceration, this increase is thought to be related to the ulcer healing effects of melatonin
grade-b Notable Very High See all 3 studies
A notable protective effect against both aspirin and heliobacter pylori induced stomach ulceration is seen with melatonin either alone or with other agents (such as omeprazole) nearing absolute protection in some instances. Although less researched, these may apply to duodenal ulcers as well
grade-b Notable - See study
Insomnia related to jet lag is reliably reduced with melatonin supplementation taken in accordance to the destination's time zone; secondary to better sleep, many other symptoms are reduced
grade-b Minor Very High See all 4 studies
An acute decrease in blood pressure occurs following melatonin ingestion, but this decrease in temporary and abolished upon standing; likely not practically relevant in an ambulatory population
grade-b Minor - See study
There appears to be a significant protective effect on life in cancer patients with solid tumors, although the protective effect does not reach 'half risk' (RR of 0.50) and fluctuates in the range of quarter risk.
grade-b Minor High See all 3 studies
Mixed influences on leptin, but melatonin may be able to increase leptin levels following acute administration
grade-b Minor High See all 4 studies
A decrease in noradrenaline appears to reliably occur after melatonin ingestion, but only at rest; this reduction is abolished upon moving
grade-b Minor Very High See all 4 studies
An increase in sleep quality can occur following treatment of conditions known to impair sleep quality (insomnia and tinnitus)
grade-b Minor Very High See all 4 studies
Melatonin may reduce symptoms associated with tinnitus in persons who suffer from the state, as assessed by questionnaire
grade-b - Very High See all 4 studies
There do not appear to be any influence of melatonin ingestion on plasma adrenaline, either inherently or from influencing the spike in adrenaline from stress
grade-c Notable - See study
A notable decrease in heartburn symptoms occurs after melatonin supplementation, thought to be related to a strengthening of the lower esophageal sphincter
grade-c Notable - See study
Has been noted to increase LES pressure, which is thought to underlie symptoms reduction in GERD
grade-c Notable - See study
Symptoms of GERD, most notably heart burn, are reduced significantly following daily melatonin ingestion at 3mg
grade-c Minor - See study
An increase in adiponectin has been noted following acute ingestion of melatonin
grade-c Minor - See study
A decrease in alertness has been noted with melatonin supplementation
grade-c Minor Moderate See 2 studies
Mixed effects on antioxidant enzymes, but there appears to be potential for melatonin to increase their content
grade-c Minor - See study
Has been noted to increase blood flow at rest
grade-c Minor Moderate See 2 studies
Mixed results, a possible increase when measuring whole-day cortisol levels (when taken in the AM) with no augmentation of stress-induced cortisol increases; may reduce cortisol if taken prior to sleep, however
grade-c Minor - See study
Serum dopamine has been noted to be slightly reduced (37%) during waking at rest, but this decrease was eliminated upon walking
grade-c Minor Very High See 2 studies
Related to the antioxidative effects, a reduction in exercise-induced oxidation has been noted
grade-c Minor - See study
An increase in fibrinogen has been noted
grade-c Minor - See study
May decrease biomarkers of oxidation in serum
grade-c Minor Very High See 2 studies
An increase in Ghrelin appears to exist following acute supplementation of melatonin
grade-c Minor Moderate See 2 studies
Appears to increase circulating levels of growth hormone
grade-c Minor - See study
A reduction in inflammatory cytokines is noted with melatonin supplementation
grade-c Minor - See study
An increase in insulin sensitivity has been noted to be secondary to reducing liver fat; an inherent influence on insulin sensitivity is uncertain
grade-c Minor - See study
Oral supplementation of melatonin (500mcg) is able to reduce intraocular pressure in otherwise healthy persons
grade-c Minor - See study
A reduction in lipid peroxidation has been noted with melatonin
grade-c Minor - See study
A decrease in liver enzymes has been noted in persons with fatty liver given melatonin supplementation, although not to a remarkable degree
grade-c Minor - See study
An increase in memory retention under periods of stress has been noted
grade-c Minor - See study
A decrease in muscle damage biomarkers (creatine kinase) has been noted with melatonin supplementation
grade-c Minor Moderate See 2 studies
A possible reduction in triglycerides to a minor degree is noted with melatonin supplementation, but this is not reliable
grade-c - - See study
No significant influence on state anxiety during stress testing
grade-c - - See study
Despite the reduction in alertness, no significant influence on sustained attention tests
grade-c - - See study
No significant influence on blood glucose levels
grade-c - - See study
No significant influence on C-reactive protein
grade-c - - See study
No significant influence on cerebral blood flow rates
grade-c - - See study
No significant influence on circulating estrogen levels
grade-c - - See study
No significant influences on HDL-C are noted with melatonin supplementation
grade-c - Very High See 2 studies
No significant influence of melatonin on heart rate during waking either at rest or ambulation
grade-c - - See study
No significant influence on IGF-1 levels
grade-c - - See study
No significant influence on fasting insulin levels noted with melatonin
grade-c - - See study
No significant influence on LDL cholesterol is noted with melatonin
grade-c - - See study
No detectable influence of melatonin on migraines that exceeds placebo
grade-c - - See study
No significant influence on prolactin concentrations
grade-c - - See study
No significant influence on resistin noted
grade-c - - See study
No significant influence on total cholesterol levels
grade-d - - See study
Too preliminary to conclude any relation to breast cancer, but urinary melatonin metabolites are positively correlated with breast cancer risk (not applied yet to supplementation)

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Frequently Asked Questions and Articles on Melatonin

Ten tips for better sleep
To feel and perform your best, you don’t just need enough sleep, you need enough quality sleep. We break down what you can do — and what you should avoid — to sleep well and wake up refreshed.

Things to Note

Is a Form Of

Primary Function:

Also Known As

N-Acetyl-5-Methoxytryptamine, Melatonine, Melovine, Melatol, Melatonex, Circadin

Goes Well With

Caution Notice

Anyone taking any neurally active agent (pharmacotherapy such as antidepressants or ADHD medication) should consult with their doctor prior to taking melatonin, as it is highly involved in many body systems and drug interactions are very likely.

  • Melatonin regulates the sleep portion of the circadian rhythm.

  • Taking melatonin at other times of the day may cause drowsiness.

Want the unbiased truth about melatonin?

We've created a fact sheet that neatly summarizes the scientific research on melatonin.

Click here to see all 387 references.