Melatonin, often referred to as the sleep hormone, is a central part of the body’s sleep-wake cycle. Its production increases with evening darkness, promoting healthy sleep and helping to orient our circadian rhythm.
The body naturally produces melatonin, but researchers and the public have increasingly taken an interest in external sources of it, such as liquids or capsules, as a way to address sleep difficulties. In the United States, melatonin is sold as a dietary supplement, and a 2012 survey by the National Institutes of Health found it to be one of the most commonly used supplements among both adults and children.
Studies have found that melatonin can improve sleep in certain cases, but it isn’t for everyone. It is important to be aware of and carefully consider melatonin’s potential benefits and downsides. People who want to use melatonin supplement should also be aware of issues related to dosage and the quality of supplements.
Melatonin is a natural hormone that is produced by the pineal gland in the brain and then released into the bloodstream. Darkness prompts the pineal gland to start producing melatonin while light causes that production to stop. As a result, melatonin helps regulate circadian rhythm and synchronize our sleep-wake cycle with night and day. In doing so, it facilitates a transition to sleep and promotes consistent, quality rest.
Melatonin created within the body is known as endogenous melatonin, but the hormone can also be produced externally. Exogenous melatonin is normally made synthetically in a laboratory and, as a dietary supplement, is most often sold as a pill, capsule, chewable, or liquid.
It is well-established that melatonin produced by the body plays a fundamental role in getting quality sleep, so it’s natural to consider whether melatonin supplements can be used to address sleeping difficulties.
Research to date has shown that melatonin supplements may be useful in certain situations for both adults and children.
In adults, research studies have found the clearest potential benefits from melatonin are for people who have sleeping problems related to Delayed Sleep-Wake Phase Disorder (DSWPD) and jet lag.
DSWPD is a circadian rhythm disorder in which a person’s sleep schedule is shifted later, often by a matter of hours. For people with this “night owl” schedule, it can be hard to get enough sleep if they have obligations, such as work or school, that force them to wake up early in the morning. Studies have indicated that low doses of melatonin taken before the desired bedtime can help people with DSWPD adjust their sleep cycle forward.
Jet lag can occur when a person travels rapidly across multiple time zones, such as on an intercontinental flight, because their body’s internal clock becomes misaligned with the local day-night cycle. Evidence from small research studies points to melatonin supplements as potentially helping to reset the sleep-wake cycle and improve sleep in people with jet lag.
Shift workers — people who work during the night — often struggle with sleep difficulties related to a misaligned circadian rhythm. Studies of melatonin in shift workers have had inconclusive results, although some people report a benefit.
There is debate about whether melatonin is beneficial in otherwise healthy adults who have insomnia, a persistent condition marked by trouble falling asleep or staying asleep. The existing research is not conclusive. Some experts reviewing it find some evidence in favor of melatonin while organizations like the American Academy of Sleep Medicine (AASM) have concluded that there is not sufficient scientific support for melatonin in reducing insomnia.
For most adults, melatonin has few notable side effects, so even when its benefits may not be clearly established, some people with sleeping problems may be inclined to try it. The best practice is to consult a doctor and have an in-depth conversation about the benefits and risks before taking melatonin.
Several research studies have indicated that melatonin may help children with sleeping difficulties fall asleep more quickly. It may also improve their total sleep time. The American Academy of Pediatrics (AAP) states that melatonin may be beneficial as a short-term tool to help children adjust to a healthier sleep schedule and establish good sleep habits.
Evidence from small studies has indicated that melatonin may be especially useful in children with certain conditions including epilepsy and some neurodevelopmental disorders such as Autism Spectrum Disorder (ASD).
Almost all reviews of the existing science acknowledge that additional research will be needed to clarify key issues about the use of melatonin in children including the optimal dosage and duration of use as well the risks of long-term side effects.
Because of the uncertainties the remain regarding melatonin’s use by children, the AAP recommends that parents work closely with their child’s doctor before administering melatonin supplements.
People with sleeping problems can benefit from taking steps to develop healthy sleep habits. Even if melatonin offers relief, improving their sleep routines and environment (mattress and bedding) — known collectively as sleep hygiene — can promote durable sleep quality improvement.
Talking with a doctor about melatonin and sleeping problems can also help reveal whether a person has an underlying sleep disorder. For example, raising poor sleep issues or excessive sleepiness may uncover a problem like sleep apnea. Melatonin isn’t a therapy for sleep apnea, but in this scenario, working with the doctor can lead to more appropriate and effective treatments.
Short-term use of melatonin has relatively few side effects and is well-tolerated by the majority of people who take it. The most commonly reported side effects are daytime drowsiness, headaches, and dizziness, but these are experienced by only a small percentage of people who take melatonin.
In children, the reported side effects of short-term use are similar as in adults. Some children may experience agitation or an increased risk of bedwetting when using melatonin.
For both children and adults, talking with a doctor before taking melatonin can help prevent possible allergic reactions or harmful interactions with other medications. People taking anti-epilepsy and blood thinning medications, in particular, should ask their physician about potential drug interactions.
The American Academy of Sleep Medicine recommends against melatonin use in people with dementia, and there is little research about its safety in women who are pregnant or breastfeeding.
There is also very little data about the long-term effects of melatonin supplements in children or adults. There is some concern that sustained use of melatonin could affect the onset of puberty in children, but research so far is inconclusive. Because the long-term effects are unknown, people should maintain an ongoing conversation with their doctor about using melatonin and the quality of their sleep and overall health.
There is no consensus about the optimal dosage of melatonin although most experts advise to avoid extremely high dosages. In studies, dosages range from .1 to 12 milligrams (mg). A typical dose in supplements is between one and three milligrams, but whether this is appropriate for any specific person depends on factors like their age and sleeping problems. You may find melatonin in dosages of micrograms (mcg), 1000 mcg is equivalent to 1 mg.
Some people experience daytime sleepiness when using melatonin as a sleep aid. If you experience this, it could be that your dosage is too high. It’s advisable to start with the lowest dosage possible and work your way up gradually under the supervision of your doctor.
The AAP advises against dosages above 3-6 mg for children and states that many young people respond to small doses of .5 to 1 mg. Some studies have found benefits to lower doses in adults as well.
Oral supplements can bring the levels of melatonin in the blood to levels much higher than is normally produced by the body. For example, dosages between 1-10 mg can raise melatonin concentrations to anywhere from 3 to 60 times typical levels. For this reason, people taking melatonin should use caution before ingesting high doses.
Melatonin is sold in the U.S. as a dietary supplement and not as a medication. This is a vital distinction because it means that melatonin products are not closely regulated by the Food and Drug Administration (FDA).
A wide range of brands with varying formulations and dosages are available over-the-counter in groceries and drugs stores, but there are important quality differences to look out for. A study that reviewed 31 melatonin supplements found major inaccuracies in dosage information; 71% of the tested products were not within 10% of their listed dosage. An incorrect dose of melatonin can have meaningful consequences including a higher risk of side effects and reduced supplement effectiveness.
Some products labeled as only containing melatonin contained impurities or other compounds, such as serotonin, that can pose health risks. Melatonin is often combined with magnesium, valerian root, or other natural sleep aids in supplements, which may further affect the accuracy of dosages and labeling.
Buyers of supplements should take care when shopping and remember that labels like “natural,” “certified,” and “verified” are not standardized or regulated. Although not a guarantee of safety, certification from organizations like US Pharmacopeia (USP), ConsumerLab.com, or the NSF International Dietary Supplement program can offer confirmation that products have been tested for contaminants or mislabeling.