Oct. 5, 2017 -- Walk the vitamin aisle of your local grocery store and you’ll find everything from flavored teas and mouth sprays to raspberry gummies and animal-shaped chews, all containing the purported sleep aide melatonin.

In all, U.S. consumers will spend more than $437 million on melatonin supplements in 2017, up from $159 million in 2010, according to Nutrition Business Journal. More than 3 million adults and a half-million children take it, and that number is expected to grow as more sleep-deprived families clamor for cheap “natural” remedies.

But with such growth also come concerns that consumers have an oversimplified view of the potent, complex hormone. Taken at the right time, in the right dose, it can, indeed, repair a sleep schedule thrown off kilter by jet lag, a long weekend filled with late nights, or certain circadian rhythm disorders.

But for insomnia that happens now and then, research shows its effectiveness is limited. And some fear that if misused, it may do harm.

Experts also question how safe it is for children. Australian experts called the increase in use among children “alarming” and warned in 2015 that parents shouldn’t give it to their children.

“A lot of people just take it right before they go to bed as if it were a sleeping pill,” says Michael Breus, PhD, a California-based clinical psychologist who specializes in sleep disorders. “It’s not that simple.”

Works for Some, Not for Others

Discovered in 1958, melatonin is a potent hormone naturally produced in the body to help regulate our circadian rhythm, or natural body clock. Light is the switch that controls it: As daylight fades, levels of melatonin begin to rise about 2 hours before bedtime, nudging us to become sleepy. In the morning, when light hits the eyes, it signals the brain to halt melatonin production, and we grow alert.

“Melatonin is a sleep regulator, not a sleep initiator,” explains Breus, author of “Good Night: The Doctor’s 4-week Program to Better Sleep and Better Health.”

Since the 1980s, dietary supplement makers have billed melatonin made in a lab as a promising sleep aid. But its effects on occasional insomnia are not significant.

One review of 15 studies involving 284 subjects found that those who took melatonin before bed fell asleep 3.9 minutes faster on average and slept 13 minutes longer. Another, of 19 studies involving 1,700 people, found melatonin users fell asleep 7 minutes faster on average and slept 8 minutes longer.

“When you are already making melatonin naturally at night, taking a little bit more exogenously is kind of like spitting in the ocean. It doesn’t do much,” says Cathy Goldstein, MD, an assistant professor of neurology at the University of Michigan Sleep Medicine Clinic. 

Alfred Lewy, MD, professor emeritus at Oregon Health & Science University and a pioneer in melatonin research, says he has found that a larger dose (3 mg) can promote sleep, but only in about one-third of people who take it. “It works for some people, but not for others. You just have to try it and find out which one you are.”

Experts do agree that melatonin can have a big effect on treating circadian rhythm disorders like delayed sleep phase disorder (extreme night owls), advanced sleep phase disorder (extreme morning larks), or shift work disorder. In these cases, the body makes melatonin too late or too early, creating a mismatch between when the person should sleep and when they feel like it.

“Say you are an extreme night owl who only begins to feel sleepy at 4 a.m. and likes to sleep until noon. You could take low-dose melatonin (0.5 mg) at 11 p.m., well before your natural melatonin kicks in. Not only will it help you feel sleepy earlier, it will start to pull your internal clock earlier too,” explains Goldstein.

Melatonin also works great for jet lag from eastward travel, says Breus, who recommends taking 0.5 mg of melatonin 90 minutes before bedtime in the place you’re traveling to.

After a weekend of staying up late and sleeping in, a low (0.3 mg) dose of melatonin late Sunday afternoon can also help you get to sleep at a regular hour and avoid the “Monday morning blues” that often happen when your days off disrupt your body clock, says Lewy. (Caution: If you are one of those people melatonin makes sleepy, don’t drive after taking it).

His research also suggests that for some patients, as little as 0.3 mg of melatonin daily in the late afternoon may ease symptoms of winter depression brought on by shorter days and shifting circadian rhythms. But because a small number of people respond better when taking the melatonin in the morning, he only recommends its use for this purpose under a doctor’s guidance.

“The challenge with melatonin is that it’s complicated. If you take it at the wrong time, it can shift your body clock in the wrong direction, and that can cause problems,” Lewy says.

Safety Concerns on the Rise

While short-term use (a few months or less) of melatonin is thought to be safe in healthy adults, it can boost blood sugar, so it is not recommended for people with diabetes, Goldstein says. Taking too much can also lead to bad dreams and grogginess the next day, and it can make many drugs less effective, including high blood pressure medications, seizure medications, and birth control pills, Breus says.

Because dietary supplements are not regulated as much as prescription drugs, quality can vary wildly from bottle to bottle. One recent study found that 71% of melatonin supplements surveyed did not contain exactly what they said on the label. Some had more than four times as much melatonin as indicated, and 26% contained the powerful neurotransmitter serotonin, a chemical found in many antidepressant medications.

When it comes to children’s use, concerns abound.

The American Association of Poison Control Centers reports that calls about melatonin have skyrocketed 114% nationwide since 2012, with 79% of the 24,000 calls in 2016 involving children. Parents often call poison control after their children have taken it unintentionally or taken too much. That can lead to nausea, diarrhea, headaches, changes in mood, lasting sleepiness the next day, and bedwetting, experts say.

Experts are also not sure if using melatonin would harm children.

In 2015, researchers from Australia published a study pointing to research that linked melatonin use on rodents to changes in puberty. The report also notes that in the early 1990s, scientists were looking into high doses of melatonin as possible human birth control because of the way it could affect the reproductive system.

The findings were in animals, and no research to date has shown similar effects in children.

"Considering the small advances melatonin provides to the timing of sleep, and considering what we know about how melatonin works in the body, it is not worth the risk to child and adolescent safety," warned lead author David Kennaway, head of the Circadian Physiology Laboratory at the University of Adelaide's Robinson Research Institute.

Some research has shown that children with developmental disorders, such as autism spectrum disorder and attention deficit hyperactivity disorder, have low nighttime melatonin levels that may help cause poor sleep patterns. If it's well-timed and under the supervision of a doctor, melatonin may help normalize their sleep and daytime behavior, Breus notes.

Breus says he would not use melatonin on otherwise healthy kids. There is little research, however, on melatonin's safety for children. 

Craig Canapari, MD, who directs the Yale Pediatric Sleep Center, says while he shares Kennaway’s concerns, he has “seen first hand the consequences of poor sleep on children and families.” He writes on his blog that he often uses it, but his goal it to help children get to sleep with as few medications as possible. He says it may be an option if:

  • Behavioral changes haven’t worked
  • Other medicals causes of insomnia have been ruled out
  • Your doctor thinks it is safe and willing to work with you on using it

And for adults with body clocks thrown off for one reason or another, it is absolutely worth trying, experts say.

Just choose your brand wisely, keep your dose well under 3 mg to avoid bad side effects, and once your sleep schedule is back on track, stop taking it.

“We really don’t know yet if it’s safe to take long-term,” says Goldstein.

Show Sources

Nutrition Business Journal.

American Association of Poison Control Centers.

National Center for Complementary and Integrated Health.

Michael J. Breus, PhD, clinical psychologist, author of “Good Night: The Doctor’s 4-week Program to Better Sleep and Better Health.”

Sleep Medicine Review, February 2005.

Plos One, May 2013.

Cathy Goldstein, MD, assistant professor of neurology, University of Michigan Sleep Medicine Clinic.

Alfred Lewy, MD, professor emeritus at Oregon Health & Science University.

PNAS, May 2006.

Journal of Clinical Sleep Medicine, 2017.

Journal of Pediatric Child Health, June 2015.

Craig Canapari, MD, "Melatonin for Children? A Guide for Parents"

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