Can the ‘Sleepy Girl Mocktail’ Actually Help You Fall Asleep?

The recipe for a “sleepy girl mocktail” is simple, and its promise is alluring: Swirl a spoonful of magnesium into a fizzing glass of seltzer and tart cherry juice, take a big sip and get the best sleep of your life.

Researchers who study supplements and sleep, however, remain skeptical.

The mocktail has gone viral on TikTok, where wellness influencers are touting it as a must-have to help you sleep. While tart cherry juice has long been pitched as a potential sleep aid, there have only been a handful of studies on its effectiveness, and most included only a small number of participants.

Tart cherries are fairly rich in melatonin, which, in theory, might mean they can induce sleep, said Marie-Pierre St-Onge, an associate professor of nutritional medicine at Columbia University. But they contain only a small fraction of the amount of melatonin in pills and gummies sold to help people sleep: One study found that 100 grams of tart cherry juice contained around .01 percent of a milligram of melatonin.

These mocktails also contain magnesium powder, which likewise has not been conclusively proven to improve sleep. In a 2022 review of nine papers on the supplement, a handful of observational studies suggested that taking magnesium is associated with better sleep, but several randomized controlled trials suggested it had no effect.

Magnesium supplements may help people with restless leg syndrome, a condition that can disrupt sleep. In that specific population, the powder might have the potential to be helpful, said Dr. Pieter Cohen, an associate professor at Harvard Medical School who studies supplements.

Some formulations of magnesium might cause diarrhea, Dr. Cohen said, so people may want to take note if they experience any gastrointestinal upset. But the components of the sleepy girl mocktail aren’t expected to cause harm — or have much of an effect at all. If the drink seems to work for you, that’s probably the placebo effect, he said. “It’s entirely magical thinking.”

But that doesn’t mean you need to stop.

“If you start taking anything and you start believing that it allows you to go to sleep — that belief is really powerful,” Dr. Cohen said.

The mocktail might be particularly appealing to those trying to cut back on alcohol during Dry or Damp January. If people are opting for the drink instead of a boozy nightcap, they’ll almost certainly have better rest, Dr. St-Onge said, since alcohol disrupts your sleep.

Sleep experts often encourage people to create a wind-down period that can offer a buffer — ideally, without screens — between work and family responsibilities and plopping into bed. Preparing and drinking the mocktail may offer just that, said Aric Prather, a psychologist and sleep specialist at the University of California, San Francisco.

“Maybe there’s something about the ritual of it — doing something for yourself, and feeling like you’re being intentional about trying to improve your sleep,” he said.

Or maybe not. Dr. Prather said that he tried the mocktail himself. “I did not notice anything,” he said, and “now I have this giant jug of tart cherry juice.”