Melatonin is a hormone that your brain produces in response to darkness.
It helps with the timing of your circadian rhythms (24-hour internal clock) and with sleep. Being exposed to light at night can block melatonin production.
Research suggests that melatonin plays other important roles in the body beyond sleep. However, these effects are not fully understood.
Melatonin dietary supplements can be made from animals or microorganisms, but most often they’re made synthetically. The information below is about melatonin dietary supplements.
For melatonin supplements, particularly at doses higher than what the body normally produces, there’s not enough information yet about possible side effects to have a clear picture of overall safety.
Short-term use of melatonin supplements appears to be safe for most people, but information on the long-term safety of supplementing with melatonin is lacking.
Also keep in mind:
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.
Possible allergic reaction risk
There may be a risk of allergic reactions to melatonin supplements.
Safety concerns for pregnant and breastfeeding women
There’s been a lack of research on the safety of melatonin use in pregnant or breastfeeding women.
Safety concerns for older people
The 2015 guidelines by the American Academy of Sleep Medicine recommend against melatonin use by people with dementia.
Melatonin may stay active in older people longer than in younger people and cause daytime drowsiness.
Melatonin is regulated as a dietary supplement
In the United States, melatonin is considered a dietary supplement. This means that it’s regulated less strictly by the Food and Drug Administration (FDA) than a prescription or over-the-counter drug would be.
In several other countries, melatonin is available only with a prescription and is considered a drug.
Products may not contain what’s listed on the label
Some melatonin supplements may not contain what’s listed on the product label. A 2017 study tested 31 different melatonin supplements bought from grocery stores and pharmacies.
For most of the supplements, the amount of melatonin in the product didn’t match what was listed on the product label.
Also, 26 percent of the supplements contained serotonin, a hormone that can have harmful effects even at relatively low levels.
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If you care about supplements, please read studies about Melatonin’s role in protecting the heart, and whether you should take Melatonin for better sleep.
For more information about nutrition, please see recent studies about why vitamin K is so important for older people, and results showing this daily vitamin is critical to cancer prevention.
