Yearning for longer, restful sleep? Supplements with ingredients like melatonin, valerian root, and magnesium promise “sleep support.” And what about the “sleepy girl mocktail” (tart cherry juice and magnesium powder, topped off with a fizzy drink), which swept TikTok this year? Here’s what the science says.

Melatonin

Melatonin is a hormone produced in the brain that helps regulate the body’s circadian rhythm. We produce more melatonin in the dark than the light, which signals the brain that it’s time to get sleepy.

In 2017, the American Academy of Sleep Medicine concluded that there wasn’t enough good evidence to say whether melatonin can help with chronic insomnia, or even whether it’s safe. A more recent review of 17 trials in older adults with chronic insomnia compared melatonin or the prescription drug ramelteon (sold as Rozerem, which works similarly to melatonin) to a placebo. Melatonin or ramelteon takers slept roughly 20 minutes longer and fell asleep about 15 minutes faster than placebo takers. (The authors didn’t report the results of melatonin and ramelteon separately.)

Melatonin may be more useful when our circadian rhythm is disrupted. For example, in a review of 10 randomized trials, people who took melatonin reported about a 20-point improvement (on a 100-point scale) on a questionnaire about symptoms of jet lag compared to those who took a placebo. 

And melatonin likely helps people with delayed sleep-wake phase disorder, who can’t fall asleep until the early hours of the morning and prefer to not wake until late morning or early afternoon. In one study, researchers randomly assigned 116 adults with delayed sleep-wake phase disorder to take a placebo or 0.5 milligrams of melatonin every day an hour before their desired bedtime for 4 weeks. According to data collected by a wrist-worn device, the melatonin takers fell asleep about 35 minutes faster—and they reported functioning better during the daytime—than the placebo takers.

Unfortunately, the melatonin you buy in the store may not be up to snuff. In 2022, when researchers tested 25 store-bought melatonin gummies, only three contained within 10 percent of the amount shown on the label. Nineteen of the other 22 supplements had 14 to 70 percent more. And another of the 25 supplements had 10.4 milligrams instead of the labeled 3 mg. And that could be a problem because experts recommend taking the lowest possible dose of melatonin. One study found that taking just 0.3 mg was enough to raise blood levels of melatonin to their normal night-time range in adults over age 50. (Taking too much may leave you feeling groggy the next day.)

Bottom line 

Melatonin might help with jet lag or for night owls who want to get to sleep earlier. For people with insomnia, melatonin likely offers only modest benefits, if any (and its long-term effects aren’t well studied). Melatonin can also interact with a number of drugs like some blood pressure medications, anti-coagulants, anti-seizure medications, or birth control so talk to your doctor before trying melatonin. To find a reliable supplement, look for quality assurance seals from USP (U.S. Pharmacopeia), NSF (NSF International), or ConsumerLab. 

And keep all supplements away from children. Calls to U.S. Poison Control Centers about (mostly unintentional) melatonin ingestion in kids increased 5-fold between 2012 and 2021. Those calls were linked to 27,795 emergency department and clinic visits, 4,097 hospitalizations, 287 intensive care unit admissions, and two deaths.

Valerian root

Valerian root is touted as a sleep aid, though the evidence is lackluster. Many studies are small, low quality, or both, and the results are inconsistent.

In one review of 29 randomized trials, the authors concluded that the highest quality studies did not find that valerian (or valerian with hops) is any better than a placebo for helping with insomnia.

In the largest study of valerian to date, researchers randomly assigned 405 adults with insomnia to take 600 milligrams of valerian or a placebo an hour before bed each night. After two weeks, the valerian takers reported no better sleep quality, time to fall asleep, or sleep duration than the placebo takers (though they did report waking up slightly fewer times during the night).

Bottom line

Don’t count on counting fewer sheep with valerian.

Magnesium

“Magnesium acts upon the nervous system and contributes to deep, restful sleep,” says Healthline.com.

Really? Only a few studies have looked at magnesium’s role in promoting sleep. Based on the results, it’s safe to say, don’t expect more zzz’s from magnesium.

In one company-funded trial, researchers randomly assigned a mere 12 older adults with no sleep problems to take a placebo or magnesium, increasing the dose from roughly 240 to 730 milligrams a day over three weeks. The volunteers spent about 6 more minutes in deep sleep the nights they took magnesium versus when they took the placebo. But other objective measures, like total time asleep, time to fall asleep, and time spent awake during the night, were no different when they took magnesium versus the placebo.

In another study, when 43 older adults with insomnia were randomly assigned to take 500 mg of magnesium or a placebo every day for 8 weeks, the magnesium takers reported falling asleep about 15 minutes faster and sleeping 37 minutes longer than the placebo takers.

But in the largest study, when 100 older people with poor sleep (based on scores on a sleep questionnaire) took either 320 mg of magnesium or a placebo every day for seven weeks, sleep scores improved equally in both groups.

Bottom line

Research on magnesium’s sleep-enhancing effects is sparse and unimpressive. And taking more than 350 mg of magnesium a day from a supplement can cause diarrhea or nausea.

Tart cherry juice

Tart cherries have gained a reputation as a sleep-inducing food because they naturally contain melatonin. But only a handful of small trials have looked at tart cherry juice and sleep. And only two of them—both industry-funded—were in people with sleep problems.

In one of the two, 15 adults over age 65 with insomnia were randomly assigned to drink one cup of a tart cherry-apple juice blend or a placebo drink first thing every morning and again an hour or two before bed. After two weeks of drinking the cherry-apple juice, the volunteers scored slightly better on an “insomnia severity index” and reported spending an hour awake throughout the night after initially falling asleep versus an hour and 20 minutes when they drank the placebo. But they didn’t report sleeping longer, falling asleep faster, or feeling less fatigued after drinking the cherry juice.

In the other study, 8 adults over age 50 with insomnia were also randomly assigned to drink a placebo or a cup of tart cherry juice every morning and another cup one or two hours before bed. After two weeks, the researchers brought the volunteers into the lab and measured their sleep for one night. It’s hard to believe what they found: The study participants slept an extra 84 minutes after two weeks of drinking tart cherry juice compared to after two weeks of drinking the placebo. But the authors didn’t report how much the volunteers slept at the beginning of the study or after each study period (they only reported the difference between groups). Without more information, it’s hard to explain those surprising results. And with only 8 people in the study, it could have been a fluke. 

Bottom line

Two very small industry-funded studies suggest that tart cherry juice might improve sleep in people with insomnia (no studies have tested tart cherry supplements in people with sleep problems). That evidence isn’t strong enough to convince us. And keep in mind that each cup of tart cherry juice clocks in at about 130 calories.