Sleep is an essential part of our lives, a fact made all the more obvious when we end up having problems with it – and a lot of people do, with about one in three adults in the US reporting that they don’t get enough rest or sleep every day.

You can try exercising, not drinking caffeine after a certain time, trying to reduce stress, but sometimes that just doesn’t cut it. Sleeping pills might offer a solution, but they aren’t for everyone – and so, some turn to natural sleep aids. But how well do they actually work?

For examples, we're going to look at one concoction that's recently gone viral, one traditional herbal remedy, and one tip your granny might've given you.

Sleepy girl mocktail

If you’re as chronically online as us, no doubt you’ll have heard of the “sleepy girl mocktail”, TikTok’s delicious answer to getting a good night’s sleep. The recipe for this doze-inducing drink? Tart cherry juice, magnesium powder, and seltzer or soda to top it off. 

It’s the first two of those ingredients that are the key to finding out whether the mocktail’s alleged effects are backed up by science – individually, they’ve been kicking about as natural sleep aids for years.

Despite that, there’s really not a lot of evidence to suggest that either magnesium or tart cherry juice will actually help you sleep better. 

A 2022 review of nine studies investigating the role of magnesium in sleep health, involving 7,582 participants, found that observational studies – where there’s no intervention from the researchers and often involving self-reported data – showed a link between magnesium and sleep quality. However, data from randomized clinical trials, which are generally considered to provide the most reliable evidence, demonstrated an uncertain relationship. 

The authors of the review concluded: “The association between dietary magnesium and sleep patterns needs well-designed randomized clinical trials with a larger sample size and longer follow-up time (more than 12 weeks) to further clarify the relationship.”

The evidence for tart cherry (Prunus cerasus) juice is slightly more positive, although still far from strong enough to clinically recommend knocking back a glass at bedtime. A 2023 meta-analysis found that “there is evidence to support significant improvements to total sleep time and sleep efficiency” by consuming tart cherries – but also noted that some individuals didn’t report a subjective benefit, and that further research is still needed.

That includes figuring out the main mechanism of action; the sleepy effects of tart cherries have been widely put down to them containing melatonin, a hormone that’s part of the body’s sleep-wake cycle and can be bought as a supplement, and tryptophan, the amino acid used in producing melatonin.

However, the meta-analysis found that to get an effect on sleep required around 100 grams (3.5 ounces) of cherries, which contains just 0.135 micrograms of melatonin and 9 milligrams of tryptophan – far below the recommended clinical doses. A sleepy girl mocktail’s levels may well be even lower – so, if it turns out tart cherry juice really does affect sleep, it could be for another reason entirely.

Valerian

Ancient Greece and Rome might not have had TikTok influencers, but they did have Galen, who was pretty influential without means of social media. When it came to treating insomnia, his prescription was valerian, a herb that’s still promoted as a natural sleep aid to this day. But has it been proven effective by modern-day science?

The evidence for valerian’s effectiveness when it comes to sleep is inconclusive. Why, when people have been using it for so long? It’s not necessarily for a lack of research into the matter, but a lack of consistent findings from such research.

A 2020 review of valerian’s effects on sleep, for example, identified 13 studies that did found the herb alone (not in a mixture with other ingredients) to be effective, and 10 studies that found it was not significantly effective compared to a control – in other words, we can’t say for sure.

As a result, if you go to the doctors for help with a bout of insomnia, you’re unlikely to be offered valerian as an alternative to other sleep aids – the American Academy of Sleep Medicine recommends against it in its clinical practice guidelines.

Warm milk

And now to find out if your grandma’s advice for sleeping well, aka a warm glass of milk (and preferably some cookies), has any truth behind it.

“Warm milk has long been believed to be associated with chemicals that simulate the effects of tryptophan on the brain. This is a chemical building block for the substance serotonin, which is involved in the sleep-wake transition,” according to Dr Charlene Gamaldo, medical director of Johns Hopkins Center for Sleep at Howard County General Hospital.

The evidence to support that belief, however, is unclear. A 2020 systematic review looking at the consumption of milk, and dairy products in general, in relation to sleep found that while their inclusion in a well-balanced diet could be considered an effective way of improving sleep quality, there were also issues with the quality of studies, and thus the strength of their evidence.

Even if it doesn’t give you better quality of sleep, a warm drink like milk might still relax you enough to make you feel sleepy, for a particularly wholesome reason. “[One] reason warm milk makes people sleepy is because it reminds you of the person who was kind enough to give it to you when you were younger,” Michael Breus, a clinical psychologist and board-certified sleep specialist, told Live Science.

The bottom line

Even if science says a natural sleep aid doesn’t work, it’s still possible for people to find that they sleep better after using one – that’s the placebo effect for you. 

For those who do turn to them, it’s also important to bear two things in mind: they may interact with medications and in the US, supplements like melatonin and valerian aren’t regulated by the Food and Drug Administration, so their contents can’t be guaranteed. United States Pharmacopeia (USP) runs a verification program for supplements, which tests products to ensure they contain the labeled ingredients in the indicated quantities. 

In cases where sleep problems persist, the best thing to do is to talk to your healthcare provider – they should be able to help find the solution that works best for you.

All “explainer” articles are confirmed by fact checkers to be correct at time of publishing. Text, images, and links may be edited, removed, or added to at a later date to keep information current. 

The content of this article is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of qualified health providers with questions you may have regarding medical conditions.