The sleepy girl mocktail: does tart cherry juice work?

The recipe is three ingredients: tart cherry juice, a scoop of magnesium powder, topped with sparkling water. It has been one of the most-shared bedtime rituals of the past few years and the drinkable face of the whole sleepmaxxing movement. Two of the three ingredients have been tested. Here’s what turned up.

Tart cherry juice

The most-cited study randomized 15 older adults with chronic insomnia in a double-blind crossover design: two weeks of a proprietary tart cherry juice blend, a two-week washout, then two weeks of placebo. Sleep was tracked by daily diary rather than by instruments.

The result was measurable but narrow. Against placebo, the juice significantly reduced minutes awake after sleep onset. It did not significantly improve sleep latency, total sleep time, or sleep efficiency, and the authors describe the effect sizes as moderate and in some cases negligible (Pigeon 2010).

The authors’ own framing is the most useful part. The effect sizes were, in their words, equal to or exceeding those seen for valerian and some melatonin studies, but “considerably less than those for evidence-based treatments of insomnia”, meaning sleeping pills and CBT-I.

So: an effect, on one outcome, in fifteen people. Not nothing. Not a treatment.

The proposed mechanism is that tart cherries contain melatonin and tryptophan, which is chemically true, though the doses are small next to a melatonin tablet. A small dose is arguably a point in its favor, since most melatonin supplements are dosed far above what the research supports.

Magnesium

The magnesium side gets more depth in its own post. The short version: three randomized trials in 151 older adults, pooled sleep-onset latency 17.36 minutes shorter than placebo, with all three trials at moderate-to-high risk of bias and the evidence rated low to very low quality (Mah 2021).

One detail bears on this recipe specifically. Those trials used oral magnesium in older adults, generally the group most likely to be running low. A healthy twenty-something with a normal diet is not the population studied.

The sparkling water

No trials. It’s there for the texture, and it may be the most underrated ingredient, for reasons below.

The verdict

Nobody has tested the combination. There is no trial of tart cherry juice plus magnesium against either alone against placebo, so any claim about the mocktail itself is extrapolation from two small, low-quality literatures.

That said, it’s cheap, pleasant, and carries essentially no risk beyond the sugar in a glass of juice and magnesium’s laxative effect at higher doses. If you enjoy it, there’s no reason to stop.

Why it might work anyway

Here’s the part the debunkings tend to skip. A ritual you perform at the same time every night, one that signals the day is over and involves sitting down with something in your hands instead of a screen, is a wind-down routine. Wind-down routines are useful.

The drink may be doing very little pharmacologically while doing quite a lot behaviorally. That isn’t a criticism, but it’s worth knowing which part is working, because it means the ingredients matter less than the consistency, and you could get the same benefit from chamomile tea and a paperback.

The higher-yield version

The things with better evidence than either ingredient here are free: a warm bath 1 to 2 hours before bed, progressive muscle relaxation, and a consistent wake time. If the problem is a busy head rather than body chemistry, the fix is somewhere else for your attention to go. Get Sleepy costs nothing either, and pairs nicely with a mocktail if you’ve already made one.

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Sources: Pigeon et al. 2010 · Mah & Pitre 2021. Check with a pharmacist before adding supplements, especially alongside other medication. This is general information, not medical advice — persistent insomnia is worth taking to a doctor.