Melatonin, a hormone produced by the body, is a popular supplement among people who believe that it helps them sleep and to adjust their body clock (jet lag, shift changes). It’s also used to address a host of problems from macular degeneration to bed wetting to migraines, despite a lack of evidence that it does. For most people in most circumstances, it poses little risk of real harm.
Except, possibly, for children. Research conducted in Australia is prompting renewed warnings for doctors and parents not to give melatonin to children for sleep problems.
Sleep researchers at the University of Adelaide in South Australia looked at how melatonin contributes to the timing of sleep — the body produces more of it as darkness begins — and determined that "[C]onsidering what we know about how melatonin works in the body, it is not worth the risk to child and adolescent safety," according to David Kennaway, head of the Circadian Physiology Laboratory at the University of Adelaide's Robinson Research Institute.
His work, published in the Journal of Paediatrics and Child Health, warned that children who were given melatonin supplements might experience serious side effects as they approach adolescence. It’s alarming, he said in a news story on the university’s website, because, “The use of melatonin as a drug for the treatment of sleep disorders for children is increasing.”
In Australia, melatonin is registered as a treatment for primary insomnia only for people 55 years and older, but it’s widely prescribed “off-label” to children with sleep disorders. In the U.S., supplements aren’t regulated, but they can have a significant effect, depending on who’s taking them, for what purpose and with what other drugs or supplements. Never give your child a vitamin, mineral or herbal supplement without checking with your doctor.
The Australian researchers found extensive evidence from laboratory studies that melatonin can cause changes in several physiological systems, including:
- reproductive (in animals).
"Melatonin is also a registered veterinary drug,” Kennaway pointed out. It’s used for changing the seasonal patterns of sheep and goats. That’s an industrial application, not a proven human health application.
"The word 'safe' is used very freely and loosely with this drug,” Kennaway said, “but there have been no rigorous, long-term safety studies of the use of melatonin to treat sleep disorders in children and adolescents.
"There is also the potential for melatonin to interact with other drugs commonly prescribed for children, but it's difficult to know without clinical trials assessing its safety."
Kennaway has been banging this drum for a long time — he has researched melatonin for 40 years, and is concerned that its risks largely have been ignored throughout the world.
To learn more about sleep problems in kids, and what to do about them, see our blog, “Is Disrupted Sleep Worse for Kids or Parents?”
For more information about nutritional supplements, see Patrick’s newsletter, “The Truth About Diet Supplements and Sports Drinks,”