Craving longer, more restful sleep? Supplements containing 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 carbonated drink) that made a splash on TikTok this year? Here’s what the science says.

Melatonin

Melatonin is a hormone produced in the brain that regulates the body’s circadian rhythm. In the dark, we produce more melatonin than in the light, which signals to the brain that it’s time to get tired.

In 2017, the American Academy of Sleep Medicine concluded that there wasn’t enough good evidence to show whether melatonin can help chronic insomnia, or whether it’s even safe. A more recent review of 17 studies in older adults with chronic insomnia compared melatonin or the prescription drug ramelteon (sold as Rozerem, which works similarly to melatonin) with a placebo. Melatonin or ramelteon users slept about 20 minutes longer and fell asleep about 15 minutes faster than placebo users. (The authors did not 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 taking melatonin reported an improvement of about 20 points (on a 100-point scale) on a questionnaire about jet lag symptoms compared to people taking 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 wake up in the 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 an hour before their desired bedtime every day for four weeks. According to data collected by a wrist-worn device, those taking melatonin fell asleep about 35 minutes faster — and reported functioning better during the day — than those taking a placebo.

Unfortunately, the melatonin you buy at the store may not be good enough. When researchers tested 25 store-bought melatonin gummies in 2022, only three contained within 10 percent of the amount listed on the label. Nineteen of the other 22 supplements contained 14 to 70 percent more. And another of the 25 supplements contained 10.4 milligrams instead of the stated 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 melatonin levels in adults over 50 to the normal nighttime range. (Taking too much can leave you feeling groggy the next day.)

Conclusion

Melatonin might help with jet lag or for night owls who want to sleep earlier. For people with insomnia, melatonin likely offers only modest benefits, if any (and its long-term effects are not well studied). Melatonin can also interact with a number of medications, such as some blood pressure medications, anticoagulants, anti-epileptic drugs, or contraceptives, so talk to your doctor before trying melatonin. To find a reliable supplement, look for quality assurance seals from USP (US Pharmacopeia), NSF (NSF International), or ConsumerLab.

And keep all dietary supplements away from children. The number of calls to U.S. poison control centers regarding (mostly accidental) melatonin ingestion in children increased fivefold between 2012 and 2021. These calls were associated with 27,795 emergency room and clinic visits, 4,097 hospitalizations, 287 intensive care unit admissions, and two deaths.

Valerian root

Valerian root is touted as a sleep aid, but the evidence for this is scant. Many studies are small, low quality, or both, and the results are inconsistent.

In a review of 29 randomized trials, the authors concluded that even the highest quality studies did not find that valerian (or valerian with hops) was better than a placebo in treating 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 one hour before bed each night. After two weeks, those taking valerian did not report better sleep quality, time to fall asleep, or sleep duration than those taking the placebo (although they did report waking up slightly less during the night).

Conclusion

Don’t expect to count fewer sheep with valerian.

magnesium

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

Really? Few studies have looked at the role of magnesium in promoting sleep. Based on the results, it’s safe to say that you shouldn’t expect more sleep from magnesium.

In a company-funded trial, researchers randomly assigned just 12 older adults with no sleep problems to take a placebo or magnesium and increased the dose from about 240 to 730 milligrams per day over three weeks. The volunteers spent about 6 minutes more in deep sleep on the nights they took magnesium than on the night they took the placebo. But other objective measures, such as total sleep time, time to fall asleep and nighttime awake time, were no different when they took magnesium compared with the placebo.

In another study, 43 older adults who suffered from insomnia were randomly assigned to receive 500 mg of magnesium or a placebo daily for eight weeks. Those taking magnesium reported falling asleep about 15 minutes faster and sleeping 37 minutes longer than those taking the placebo.

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

Conclusion

Research on the sleep-promoting effects of magnesium is sparse and unimpressive. And taking more than 350 mg of magnesium per day from a supplement may cause diarrhea or nausea.

Sour cherry juice

Tart cherries are considered a sleep-inducing food because they naturally contain melatonin. However, only a few small studies have looked at the connection between tart cherry juice and sleep. And only two of them – both funded by the industry – were conducted on people with sleep problems.

In one of the two studies, 15 adults over 65 with insomnia were randomly assigned to drink a cup of a tart cherry-apple juice mix or a placebo drink first thing each morning and one to two hours before bedtime. After drinking the cherry-apple juice for two weeks, the volunteers scored slightly higher on an “insomnia severity index,” reporting being awake for an hour throughout the night after initially falling asleep, compared with an hour and 20 minutes when they drank the placebo. But they did not report sleeping longer, falling asleep faster or feeling less tired after drinking the cherry juice.

In the other study, 8 adults over 50 with insomnia were also randomly assigned to receive either a placebo or a cup of tart cherry juice each morning and another cup an hour or two before bed. After two weeks, researchers brought the volunteers into the lab and measured their sleep overnight. What they found is hard to believe: Study participants slept 84 minutes longer after two weeks of drinking tart cherry juice than after two weeks of drinking the placebo. However, the authors did not report how much the volunteers slept at the start of the study or after each study period (they only reported the differences between groups). Without more information, these surprising results are difficult to explain. And since only 8 people participated in the study, it could have been a coincidence.

Conclusion

Two very small, industry-funded studies suggest that tart cherry juice might improve sleep in people with insomnia (there are no studies testing tart cherry supplements in people with sleep problems). This evidence isn’t compelling enough to convince us. And keep in mind that each cup of tart cherry juice contains about 130 calories.