Melatonin

From WikiMD

Melatonin is a hormone made by the pineal gland (tiny organ near the center of the brain). Melatonin helps control the body’s sleep cycle, and is an antioxidant. It is also made in the laboratory and sold as a supplement.

Information about Melatonin

Melatonin is a hormone produced by the pineal gland that has multiple effects including somnolence, and is believed to play a role in regulation of the sleep-wake cycle.  Melatonin is available over-the-counter and is reported to have beneficial effects on wellbeing and sleep. 

Liver safety of Melatonin

Melatonin has not been implicated in causing serum enzyme elevations or clinically apparent liver injury.  

Mechanism of action of Melatonin

Melatonin is a small molecular weight amine (N-actyl-5-methoxytryptamine) synthesized in the pineal gland from serotonin (5-HT).  Melatonin is released into the circulation in a circadian pattern, the plasma levels being low during the day and high at night.  In persons with normal sleep-wake patterns, peak melatonin values are present between 2:00 am and 4:00 am and drop before light onset in the morning.  Melatonin acts by engagement of melatonin receptors (MT-1 and MT-2) causing a reduction of body temperature and alternation of brain monoamine levels, which can induce somnolence.  Melatonin also has potent antioxidant activity and may have reproductive effects and modulate immune reactions. 

Clinical use of Melatonin

Melatonin has been proposed as therapy of sleep disturbances including insomnia and jet lag, but it has not been approved for this indication in the United States.  Melatonin is considered a nutritional supplement and is available over-the-counter in multiple generic forms and formulations.  Melatonin is also found in many herbal and nutrition supplement mixtures. 

Clinical use of Melatonin

A common dose is 10 mg once daily, taken orally one to three hours before sleep time. 

Jet lag

Jet lag affects people when they travel by air across multiple time zones. With jet lag, you may not feel well overall and you may have disturbed sleep, daytime tiredness, impaired functioning, and digestive problems.

Research suggests that melatonin supplements may help with jet lag. This is based on medium-sized reviews from 2010 and 2014.

Four studies that included a total of 142 travelers showed that melatonin may be better than a placebo (an inactive substance) in reducing overall symptoms of jet lag after eastward flights. Another study of 234 travelers on eastward flights looked at only sleep quality and found low-quality evidence that melatonin may be better than placebo for improving sleep quality.

Two studies that included a total of 90 travelers showed that melatonin may be better than a placebo in reducing symptoms of jet lag after westward flights.

Delayed sleep-wake phase disorder (DSWPD)

People with DSWPD have trouble falling asleep at the usual times and waking up in the morning. They typically have difficulty getting to sleep before 2 to 6 a.m. and would prefer to wake up between 10 a.m. and 1 p.m.

Melatonin supplements appear to help with sleep in people with DSWPD, but it’s uncertain whether the benefits outweigh the possible harms. This is based on a clinical practice guideline, a small review, and a more recent study.

In 2015, the American Academy of Sleep Medicine recommended melatonin supplements given at specific times for DSWPD. The recommendation was a weak one, and it came with uncertainty about whether the benefits of melatonin outweigh its potential harms.

A 2016 review that looked at a small number of people (52) from two studies showed that melatonin supplements reduced the time it took for people with DSWPD to fall asleep when compared to placebo. On average, it took about 22 minutes less for them to fall asleep.

A 2018 randomized controlled trial that lasted 4 weeks and included 307 people with DSWPD found that taking melatonin 1 hour before the desired bedtime combined with going to bed at a set time led to several improvements. Those improvements included falling asleep an average of 34 minutes earlier, better sleep during the first third of the night, and better daytime functioning.

Some sleep disorders in children

Sleep problems in children can have undesirable effects on their behavior, daytime functioning, and quality of life. Children with certain conditions, such as atopic dermatitis, asthma, attention-deficit hyperactivity disorder (ADHD), or autism spectrum disorder (ASD), are more prone to sleep problems than other children.

There are no overall guidelines on the best approach to improving sleep in children. However, guidelines for specific conditions recommend behavioral treatments, such as good bedtime habits and parent education, as an initial treatment that may be supplemented with medicines.

A 2019 review looked at 18 studies of melatonin supplements that included a total of 1,021 children. Most of the studies were small, and all were relatively brief (1 to 13 weeks). Overall, the studies showed that melatonin was better than placebo for improving both the time to fall asleep and total sleep. The effects of melatonin on behavior and daytime functioning, however, weren’t clear because the studies used different ways to measure these outcomes.

The list below shows the review’s results on melatonin’s short-term effects for children with specific conditions.

Children with ASD fell asleep 37 minutes earlier and slept 48 minutes longer.

Children with ADHD fell asleep 20 minutes earlier and slept 33 minutes longer.

Children with atopic dermatitis fell asleep 6.8 minutes earlier and slept 35 minutes longer

Children with chronic sleep-onset insomnia fell asleep 24 minutes earlier and slept 25 minutes longer.


Because there aren’t many studies on children and melatonin supplements, there is a lot we don’t know about the use of melatonin in children. For example, there are uncertainties about what dose to use and when to give it, the effects of melatonin use over long periods of time, and whether melatonin’s benefits outweigh its possible risks. Because melatonin is a hormone, it’s possible that melatonin supplements could affect hormonal development, including puberty, menstrual cycles, and overproduction of the hormone prolactin, but we don’t know for sure.

Because of these uncertainties, it’s best to work with a health care provider if you’re considering giving a child melatonin for sleep problems.

Anxiety before and after surgery

Anxiety before and after surgery happens in up to 80 percent of patients.

Melatonin supplements appear to be helpful in reducing anxiety before surgery, but it’s unclear if it helps to lower anxiety after surgery. This is a based on a 2015 review.

The 2015 review looked at 12 studies that involved 774 people and assessed melatonin supplements for treating anxiety before surgery, anxiety after surgery, or both. The review found strong evidence that melatonin is better than placebo at reducing anxiety before surgery. Melatonin supplements may be as effective as standard treatment (the antianxiety medicine midazolam). However, the results on melatonin’s benefits for reducing anxiety after surgery were mixed.

Interactions with Medicines

As with all dietary supplements, people who are taking medicine should consult their health care providers before using melatonin. In particular, people with epilepsy and those taking blood thinner medications need to be under medical supervision when taking melatonin supplements.

The possible long-term side effects of melatonin use are unclear.

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Herbal and dietary supplements

Chinese and Other Asian Herbal Medicines

Multi-Ingredient Nutritional Supplements

See also Nutritional supplements

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