The Evidence on Melatonin for Insomnia
Research helps explain if the supplement actually works.
Posted March 29, 2018
If you have ever experienced insomnia, you know the agony of trying to fall asleep when your body simply will not cooperate. It is a common problem; an estimated 10 percent of people living in Western society are diagnosed with a significant sleep disorder and another 25 percent experience problems most days with sleeping or feeling tired during the day.
In recent years, melatonin has become a popular solution. The hormone is naturally produced by the body to regulate the circadian rhythm, including controlling the sleep-wake cycle. (Our bodies make melatonin when it’s time to fall asleep, and stop producing it when it’s time to wake up in the morning.) In the United States and Canada, melatonin is sold over-the-counter as a dietary supplement.
Researchers have conducted hundreds of studies about the effects of melatonin for a wide range of uses—from jet lag to sleep disorders in everyone from children to geriatric patients. And in the past several years, several groups of researchers have examined the body of evidence on melatonin. Here’s what they found:
A review published in the journal Sleep Medicine Reviews in 2017 combined the evidence from 12 randomized and controlled trials that looked at how well melatonin works to treat primary sleep disorder in adults. Reviewers found convincing evidence that melatonin is effective in helping people fall asleep faster and helped blind people regulate their sleep patterns.
For children, a review published in 2014 in the Journal of Pediatric Psychology combined the evidence from 16 randomized controlled trials to find out if melatonin could help kids with sleep problems. Researchers found that melatonin helped children suffering from insomnia to fall asleep more quickly, wake up fewer times each night, fall back to sleep faster when they did wake up, and get more sleep each night.
An older systematic review, published by the Cochrane Collaboration in 2002, found melatonin is effective in preventing and reducing the symptoms of jet lag, especially for travelers who are crossing five or more time zones heading east.
On the whole, there is solid evidence that melatonin can help people to fall asleep and to regulate their internal body clocks. In the short term, there is no evidence of serious adverse effects. All three reviews note there is no good evidence about the long-term effects of taking melatonin.
But there is a complication: Because melatonin is sold as a dietary supplement, its manufacture is not regulated by the U.S. Food and Drug Administration.
A study published last year in the Journal of Clinical Sleep Medicine analyzed the content of 31 melatonin supplements from different brands. Researchers found that the actual content of the melatonin supplements ranged widely compared to their labels—from 83 percent less than advertised to 478 percent more than advertised. Less than 30 percent of the supplements tested contained the labeled dose. And researchers didn’t find any patterns of variations associated with specific brands, which makes it virtually impossible for consumers to know how much melatonin they are actually getting.
In addition, eight of the supplements in the study contained a different hormone—serotonin—that is used in treating depression and some neurological disorders. Unknowingly taking serotonin can lead to serious side effects.
Dosing is also a problem. A 2005 systematic review published in the journal Sleep Medicine Reviews found that melatonin is most effective at a dose of 0.3 milligrams. But commercially-available melatonin pills contain up to 10 times the effective amount. At that dose, melatonin receptors in the brain become unresponsive.
The take-home message: While melatonin may help with your sleep problems, there is no sure-fire way to purchase a pure, precise dose of the hormone at this time.