Melatonin is a natural hormone that the brain releases in response to changes in light. It helps regulate the body's internal clock, signaling that it is time to go to sleep.
Melatonin supplements may help with a wide range of sleep issues, including insomnia, shift work sleep disorder, and sleep problems in children.
In this article, learn more about melatonin for sleep, including its side effects, the right dosage, and how it works.
Melatonin is a hormone that tells the body that it is time to sleep. In people who do not have problems sleeping, the body follows an internal clock of roughly 24 hours called a circadian rhythm.
Changes in light and temperature help tell the body when to feel tired. The brain releases melatonin when it is dark, suggesting that melatonin helps regulate sleepiness in these conditions.
Exposure to light may block the production of melatonin, which is why it is important to sleep in a dark room.
A 2015 study examined zebrafish with a rare mutation that stopped them from producing melatonin. These fish slept very little, even when researchers ensured that they had adequate exposure to darkness.
These findings suggest that the body depends on melatonin, not just changes in light, to help it get to sleep.
Melatonin supplements may improve sleep by boosting melatonin levels in people whose bodies do not produce enough of this hormone.
These supplements may also improve sleep in people who produce enough melatonin but still struggle to sleep for other reasons.
Melatonin changes how the body responds to darkness, helping it enter a rhythm of nighttime drowsiness.
Exposure to light at night — including light from computer and television screens — may suppress the body's natural melatonin production and disrupt sleep.
Likewise, people who sleep during the day because they work at night may not produce melatonin when it is time to sleep. Melatonin supplements can help counteract this effect.
Research consistently shows that melatonin can help people sleep longer and fall asleep more quickly.
A 2013 meta-analysis that included 1,683 study participants found that melatonin decreased the amount of time that it took the participants to fall asleep compared with a placebo. It also increased the duration of their sleep.
Other research has suggested that melatonin can improve sleep in people with:
The ideal dosage for melatonin varies from person to person. Various factors, such as body weight, metabolism, and overall health, may also influence the way that the body responds to melatonin.
The National Sleep Foundation recommend a dosage of between 0.2 milligrams (mg) and 5 mg for adults each day, which it is best to take 1 hour before going to bed.
People can try starting with a low dose and looking for any adverse side effects. They can then gradually increase the dose until their sleep improves, if necessary. It is important not to take more than 5 mg unless a doctor recommends a higher dose.
One of the most common side effects of melatonin is drowsiness. Some people may notice that they feel sleepy or groggy the morning after taking melatonin.
Taking melatonin earlier in the evening or reducing the dose may help a person wake up feeling refreshed.
Other possible side effects include:
Although melatonin is a natural chemical, it is important to treat it the same as any other medication. It is possible for melatonin to interact harmfully with other drugs by reducing their effectiveness, triggering negative side effects, or changing the way that the body metabolizes the drug. People who take other medications should talk to a doctor before trying melatonin.
As with any medication, an allergic reaction is possible. People with a history of allergic reactions to supplements should avoid melatonin.
Anyone who notices signs of an allergic reaction, such as itching or hives, should contact a doctor. If a person has trouble breathing or feels as though they are choking, they should go to the emergency room or call 911.
Very limited data suggest that melatonin might increase the risk of seizures, but other studies have found that it may actually lower this risk.
People with seizure disorders or a family history of seizures should consult a doctor before trying melatonin.
Some research involving children also suggests that melatonin could alter the function of the hypothalamic-pituitary-gonadal axis. In turn, this could change how the body produces or metabolizes hormones, potentially affecting the child's growth. However, this research is inconclusive.
Before trying melatonin, parents and caregivers should help a child adopt good sleep practices, such as:
- maintaining a regular, predictable sleep routine
- scheduling dinner at least 2 hours before bedtime
- avoiding caffeine and other stimulant drugs
- keeping the sleep environment quiet, dark, and cool
- not using screens for at least an hour before bedtime
Choosing the right melatonin dosage for children can be challenging as the drug is a supplement with no approved dosing guidelines. When in doubt, it is best to consult a doctor.
The authors of a paper on the use of melatonin in Canada noted that typical doses were 0.75 mg to 1 mg in children younger than 6 years, 1.5 mg to 3 mg in older children, and 5 mg to 10 mg in adolescents. It is best for children to take it between 30 and 60 minutes before bedtime.
They also stated that there was no evidence to support the use of melatonin in children younger than 2 years.
Although there is no reason to suspect that melatonin might cause long-term harm, no research has established that it is safe to use for extended periods.
For this reason, parents and caregivers should use melatonin for the shortest possible period and consult a doctor before giving their child melatonin or any other supplement.
Sleep difficulties are common. While some people only experience occasional sleeplessness, others deal with chronic sleep problems. Melatonin offers a natural solution that mimics the hormone that the brain already produces.
For many people, melatonin is an effective alternative to prescription medications for sleep. However, people should treat melatonin the same as any other medication and carefully watch for side effects.
Melatonin supplements for sleep are available in pharmacies, some natural health stores, and online.