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Roughly 50–70 million Americans are affected by poor sleep. In fact, according to some studies, up to 30% of adults in the United States report that they sleep for less than 6 hours each night. (1, 2).

Although it’s a common problem, poor sleep can have severe consequences.

Poor sleep can deplete your energy, lower your productivity, and increase the risk of diseases such as high blood pressure and diabetes (1).

Melatonin is a hormone that tells your body when it’s time to head to bed. It’s also become a popular supplement among people struggling to fall asleep.

This article explains how melatonin works as well as its safety and how much to take.

What is melatonin?

Melatonin is a hormone that your body makes naturally.

It’s produced by the pineal gland in the brain, but it’s also found in other areas, such as the eyes, bone marrow, and gut (3).

It’s often called the “sleep hormone,” as high levels can help you fall asleep.

However, melatonin itself won’t knock you out. It simply lets your body know that it’s nighttime so you can relax and fall asleep easier (4).

Melatonin supplements are popular among people with insomnia and jet lag. You can get melatonin in many countries without a prescription.

Melatonin is also a powerful antioxidant, which may provide a variety of other benefits.

In fact, it may help:

  • support eye health
  • treat stomach ulcers and heartburn
  • ease tinnitus symptoms
  • raise growth hormone levels in men
Summary

Melatonin is a hormone that’s naturally made by the pineal gland. It helps you fall asleep by calming the body before bed.

How does it work?

Melatonin works together with your body’s circadian rhythm.

In simple terms, the circadian rhythm is your body’s internal clock. It lets you know when it’s time to:

  • sleep
  • wake
  • eat

Melatonin also helps regulate your body temperature, your blood pressure, and the levels of some hormones (5, 6, 7).

Melatonin levels start to rise in your body when it’s dark outside, signaling to your body that it’s time to sleep (8).

It also binds to receptors in the body and can help you relax.

For instance, melatonin binds to receptors in the brain to help reduce nerve activity.

It can reduce levels of dopamine, a hormone that helps you stay awake. It’s also involved in some aspects of the day-night cycle of your eyes (9, 10, 11).

Although the exact way melatonin helps you fall asleep is unclear, research suggests these processes can help you fall asleep.

Conversely, light suppresses melatonin production. This is one way that your body knows it’s time to wake up (12).

As melatonin helps your body prepare for sleep, people who don’t make enough of it at night can have trouble falling asleep.

There are many factors that may cause low melatonin levels at night.

Stress, smoking, exposure to too much light at night (including blue light), not getting enough natural light during the day, shift work, and aging all affect melatonin production (13, 14, 15, 16).

Taking a melatonin supplement may help counter low levels and normalize your internal clock.

Summary

Melatonin works closely with your body’s circadian rhythm to help prepare you for sleep. Its levels rise at nighttime.

It can help you fall asleep

While additional research is needed, current evidence indicates that taking melatonin before bed may help you get to sleep (17, 18, 19, 20).

For example, an analysis of 19 studies on people with sleep disorders found that melatonin helped reduce the time it took to fall asleep by an average of 7 minutes.

In many of these studies, people also reported significantly better quality of sleep (19).

Additionally, melatonin can help with jet lag, a temporary sleep disorder.

Jet lag occurs when your body’s internal clock is out of sync with the new time zone. Shift workers may also experience jet lag symptoms since they work during a time normally saved for sleep (21).

Melatonin can help reduce jet lag by syncing your internal clock with the time change (22).

For instance, an analysis of nine studies explored the effects of melatonin in people who traveled through five or more time zones. Scientists found that melatonin was remarkably effective at reducing the effects of jet lag.

The analysis also found that both lower doses (0.5 milligrams) and higher doses (5 mg) were equally effective at reducing jet lag (23).

Summary

Evidence shows that melatonin can help you fall asleep faster. In addition, it can help people with jet lag get to sleep.

Other health benefits

Taking melatonin may provide you with other health benefits as well.

May support eye health

Healthy melatonin levels may support eye health.

It has powerful antioxidant benefits that could help lower the risk of eye diseases, such as age-related macular degeneration (AMD) (24).

In one study, scientists asked 100 people with AMD to take 3 mg of melatonin over 6 to 24 months. Taking melatonin daily helped protect the retinas and delay damage from AMD, without any significant side effects (25).

May help treat stomach ulcers and heartburn

The antioxidant properties of melatonin may help treat stomach ulcers and alleviate heartburn (26, 27).

A study with 21 participants found that taking melatonin and tryptophan along with omeprazole helped stomach ulcers caused by the bacteria H. pylori heal faster.

Omeprazole is a common medication for acid reflux and gastroesophageal reflux disease (GERD) (28).

In another study, 36 people with GERD were given either melatonin, omeprazole, or a combination of both to treat GERD and its symptoms.

Melatonin helped reduce heartburn and was even more effective when combined with omeprazole (27).

Future studies will help clarify how effective melatonin is in treating stomach ulcers and heartburn.

May reduce symptoms of tinnitus

Tinnitus is a condition characterized by a constant ringing in the ears. It’s often worse when there’s less background noise, such as when you’re trying to fall asleep.

Interestingly, taking melatonin may help reduce symptoms of tinnitus and help you get to sleep (29).

In one study, 61 adults with tinnitus took 3 mg of melatonin before bed for 30 days. It helped reduce the effects of tinnitus and significantly improved sleep quality (30).

May help increase growth hormone levels in men

Human growth hormone (HGH) is naturally released during sleep. In healthy young men, taking melatonin may help increase HGH levels.

Studies have shown that melatonin can make the pituitary gland, the organ that releases HGH, more sensitive to the hormone that releases HGH (31, 32).

In addition, studies have shown that both lower (0.5 mg) and higher (5 mg) melatonin doses are effective at stimulating HGH release (32).

Another study found that 5 mg of melatonin combined with resistance training increased the levels of HGH in men while lowering the levels of somatostatin, a hormone that inhibits HGH (33).

Summary

Melatonin may support eye health, ease tinnitus symptoms, treat stomach ulcers and heartburn, and increase growth hormone levels in young men.

How to take melatonin

If you’d like to try melatonin, start with a lower dose supplement.

For instance, start with 0.5 mg (500 micrograms) or 1 mg 30 minutes before going to bed. If that doesn’t seem to help you fall asleep, try increasing your dose to 3–5 mg.

Taking more melatonin than this likely won’t help you fall asleep faster. The goal is to find the lowest dose that’ll help you fall asleep.

However, it’s best to follow the instructions that come with your supplement.

Melatonin is widely available in the United States. You’ll need a prescription for melatonin in other places, such as the European Union and Australia.

Summary

If you want to try melatonin, start with 0.5 mg (500 micrograms) or 1 mg 30 minutes before bed. If that doesn’t work, try increasing it to 3–5 mg or follow the instructions on the supplement.

Safety and side effects

Current evidence suggests that melatonin supplements are safe, nontoxic, and not addictive (34, 35).

That being said, some people may experience mild side effects, such as:

  • dizziness
  • headaches
  • nausea

Melatonin may also interact with a variety of medications. These include (36, 37, 38, 39, 40, 41, 42, 43):

  • sleep aids or sedatives
  • blood thinners
  • anticonvulsants
  • blood pressure medication
  • antidepressants
  • oral contraceptives
  • diabetes medications
  • immunosuppressants

If you have a health condition or take any of the above medications, it’s best to check with your doctor before beginning a supplement.

There’s also some concern that taking too much melatonin will stop your body from making it naturally.

However, several studies have found that taking melatonin won’t affect your body’s ability to make it on its own (44, 45, 46).

Summary

Current studies show that melatonin is safe, nontoxic, and not addictive. However, it may interact with medications, such as blood thinners, blood pressure medications, and antidepressants.

Melatonin and alcohol

Dips in melatonin can occur following evening alcohol consumption. One study in 29 young adults found that alcohol consumption 1 hour before bed could reduce melatonin levels by up to 19% (47).

Low levels of melatonin have also been detected in individuals with alcohol use disorder (AUD).

Further, melatonin levels rise more slowly in individuals with an alcohol dependency, meaning it can be harder to get to sleep (48, 49).

However, melatonin supplementation doesn’t improve sleep in these cases. A study of people with AUD found that, compared to placebo, receiving 5 mg of melatonin a day for 4 weeks didn’t improve sleep (50).

It’s been proposed that the antioxidant effects of melatonin may help to prevent or treat alcohol-related illnesses. However, additional research is needed to test this claim (51).

Summary

Drinking before bed can decrease your levels of melatonin and may affect sleep.

While low levels of melatonin are seen in those with alcohol use disorder (AUD), melatonin supplementation doesn’t improve their sleep.

Melatonin and pregnancy

Your natural melatonin levels are important during pregnancy. In fact, melatonin levels fluctuate throughout a pregnancy (52, 53).

During the first and second trimester, the nighttime peak of melatonin decreases.

However, as the due date approaches, melatonin levels begin to rise. At term, melatonin levels reach a maximum. They’ll return to pre-pregnancy levels after delivery (53).

Maternal melatonin is transferred to the developing fetus where it contributes to the development of circadian rhythms as well as both the nervous and endocrine systems (5254).

Melatonin also appears to have a protective effect for the fetal nervous system. It’s believed that the antioxidant qualities of melatonin protect the developing nervous system from damage due to oxidative stress (54).

While it’s clear that melatonin is important during the course of a pregnancy, there are limited studies on melatonin supplementation during pregnancy (55).

Because of this, it’s currently not recommended that pregnant women use melatonin supplements (5).

Summary

Melatonin levels change throughout pregnancy and are important for the developing fetus. However, melatonin supplementation isn’t currently recommended for pregnant women.

Melatonin and babies

During pregnancy, maternal melatonin is transferred to the developing fetus. However, following birth, a baby’s pineal gland begins making its own melatonin (56).

In babies, melatonin levels are lower during the first 3 months after birth. After this period, they increase, likely due to the presence of melatonin in breast milk (57).

Maternal melatonin levels are highest at night. Because of this, it’s believed that breastfeeding in the evening may help to contribute to the development of a baby’s circadian rhythms (58).

While melatonin is a natural component of breast milk, no data exist on the safety of melatonin supplementation while breastfeeding. Because of this, it’s often recommended that breastfeeding mothers avoid using melatonin supplements (5, 59).

Summary

Although babies begin producing their own melatonin after birth, levels are initially low and are naturally supplemented by maternal breast milk. Melatonin supplements aren’t recommended for nursing mothers.

Melatonin and children

It’s estimated that up to 25% of healthy children and adolescents have trouble falling asleep.

This number is higher — up to 75% — in children with neurodevelopmental disorders, such as autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD) (60).  

The effectiveness of melatonin in children and adolescents is still being investigated.

One literature review looked at seven trials of melatonin use in this population.

Overall, it found that children receiving melatonin as a short-term treatment had a better sleep onset than the children receiving a placebo. This means that it took them less time to fall asleep (61).

A small study followed up on people who had been using melatonin since childhood, for a period of about 10 years. It found that their sleep quality wasn’t notably different from that of the control group who hadn’t used melatonin.

This suggests that sleep quality in people who had used melatonin as children normalized over time (62).

Studies of melatonin for children with neurodevelopmental disorders, such as ASD and ADHD, are ongoing, and the results have been varied.

Generally, they’ve found that melatonin may help children diagnosed with a neurodevelopmental disorder sleep longer, fall asleep faster, and have better sleep quality (63, 64, 65).

Melatonin is well tolerated in children. However, there’s some concern that long-term use may delay puberty, as a natural decline of evening melatonin levels is associated with the onset of puberty. More studies are needed to investigate this (43, 66).

Melatonin supplements for children are often found in the form of gummies.

If giving melatonin to a child, aim to give it to them 30 to 60 minutes before bedtime. Dosage can vary by age with some recommendations including 1 mg for infants, 2.5 to 3 mg for older children, and 5 mg for young adults (60).

Overall, more research is needed to determine the optimal dosage and efficacy of melatonin use in children and adolescents.

Additionally, because researchers don’t yet understand the long-term effects of melatonin use in this population, it may be best to try to implement good sleep practices before trying melatonin (57, 60, 67).

Summary

Melatonin may help to improve sleep onset in children as well as various aspects of sleep quality in children with neurodevelopmental disorders.

However, the long-term effects of melatonin treatment in children are still unknown.

Melatonin and older adults

Melatonin secretion decreases as you age. These natural declines may potentially lead to poor sleep in older adults (68, 69).

As with other age groups, the use of melatonin supplementation in older adults is still being investigated. Studies indicate that melatonin supplementation may improve sleep onset and duration in older adults (70).

One literature review found that there’s some evidence for using low-dose melatonin for older people who are having trouble sleeping. However, more research is needed (71).

Melatonin may also help in people with mild cognitive impairment (MCI) or Alzheimer’s disease.

Some studies have shown that melatonin can potentially improve sleep quality, feelings of “restedness,” and morning alertness in individuals diagnosed with these conditions. Research into this topic is ongoing (72, 73).

While melatonin is well tolerated in older adults, there are concerns about increased daytime drowsiness. Additionally, the effects of melatonin may be prolonged in older individuals (74).

The most effective dose of melatonin for older adults hasn’t been determined.

A recent recommendation suggests that a maximum of 1 to 2 mg be taken 1 hour prior to bedtime. It’s also recommended that immediate-release tablets be used to prevent prolonged levels of melatonin in the body (69, 74, 75).

Summary

Melatonin levels naturally decrease as you get older. Low-dose supplementation with immediate-release melatonin may help to improve sleep quality in older adults.

The bottom line

Melatonin is an effective supplement that can help you fall asleep, especially if you have insomnia or jet lag. It may have other health benefits as well.

If you’d like to try melatonin, start with a lower dose of 0.5–1 mg, taken 30 minutes before bed. If that doesn’t work, you can increase your dose to 3–5 mg.

Melatonin is generally well tolerated, although there’s a potential for mild side effects. Some medications may interact with melatonin.

Talk to your doctor if you’re taking these medications.

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