Magnesium Supplements Are a Buzzy New Sleep and Anxiety Aid. Do They Work?

Everyone on TikTok is bleary-eyed and anxious, it sometimes seems. The generations that dominate the app—Gen Z and Millennials—are also those most beleaguered by anxiety, which is closely tied to sleep disturbances. It’s little wonder, then, that supposed sleep aids—like tart cherry juice, brown noise, melatonin, and CBD—are constant fixtures on the social media platform.

Now, the app’s wellness community has latched onto the latest supplement touted to heal both poor sleep and anxiety: magnesium glycinate, one of nearly a dozen over-the-counter supplements that can be used to boost the body’s levels of magnesium. Content creators insist that it helps them go to bed hours earlier than they usually do, eases insomnia, and lets them unwind at the end of the day. One nurse practitioner on the app called magnesium glycinate her “holy grail supplement.”

So does it really work?

What is magnesium?

Magnesium, of course, isn’t new. It’s a mineral element that you already have in your body, thanks to foods like nuts, seeds, beans, and certain vegetable and dairy items. It works within the cells of multiple body systems to keep muscles, nerves, and other parts functioning properly. Someone trying to sell you supplements might tell you that as many as half of U.S. adults are magnesium-deficient, and while this is technically true, most of us still get enough to prevent any real noticeable effects, says Emily Tarleton, a registered dietitian and researcher at Northern Vermont University. Significant magnesium deficiencies are much less common and often come with symptoms like fatigue, weakness, and nausea. Some researchers, however, have also suggested that there could be connections between even mild magnesium deficiency and sleep disorders.

In nature, magnesium is always found in combination with other elements, meaning that there are many ways to deliver it into the body. Magnesium products and supplements mirror this diversity of form. You can buy capsules (like magnesium citrate), beverage additives (like magnesium lactate), or salts, which include magnesium sulfate (aka Epsom salt) and are designed to deliver small amounts of the mineral through the skin. Magnesium glycinate is popular because it’s among the capsule forms that are the most bioavailable, meaning that a larger amount of the mineral can be used by the body.

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Do magnesium supplements improve mental health or sleep?

Tarleton is one of the few researchers who have studied magnesium’s effect on depression in a randomized clinical trial, the gold standard for medication studies. In her 2017 study, she found that people who took 248 mg of elemental magnesium from magnesium chloride tablets each day reported improvements in feelings of depression over six weeks. The same year, a review of 18 small studies found that people who took various magnesium supplements reported improvements in symptoms of anxiety. In Tarleton’s study, “one of the other side effects was increased sleep,” she says. Though she hasn’t studied magnesium supplements’ effects directly on sleep, it makes sense to her that the mineral would work as a sleep aid, particularly in the more bioavailable forms like magnesium glycinate and magnesium chloride. “Magnesium plays a huge role in muscle contraction,” she says. “Athletes will sometimes use it for muscle cramping. So our theory is that the muscle relaxation side effect could help with sleep.”

When sleep quality has appeared in magnesium supplementation research, it’s most often as a side effect. In studies where magnesium has been given to people with migraines, polycystic ovary syndrome (PCOS), and a few other health conditions, sleep improvements have sometimes been reported but are rarely formally tracked.

A few studies have looked at magnesium supplements exclusively as an insomnia treatment, but they have all been too small and targeted to specific populations to draw conclusions from. One such study in 2012 included only elderly participants and had a sample size of only 46 people. Another more recent study from 2019 included magnesium as an insomnia treatment, but only as part of a supplement that also contained melatonin and vitamin B. In 2022, the authors of a review that analyzed all studies of magnesium as an insomnia treatment concluded that without more and longer-lasting research, no definitive link between magnesium and sleep could be drawn.

Magnesium’s biggest starring role in the health world has long been for the treatment of migraines; certain formulas and strengths are made available via prescription to those who suffer from the attacks. Current theories about how magnesium works to alleviate these symptoms primarily suggest that magnesium gives the brain a sort of boost to resume normal function, including moderating the release of chemical signals and drawing healing factors into the area. While there’s no firm evidence that any of these processes would also apply to the sleep-addled mind, Tarleton says that it’s plausible.

How to use magnesium safely

If you want to try magnesium for sleep, relaxation, or any other reason, it’s important to make sure you actually know how much you’re taking. And because supplements aren’t regulated in the same way medications are, magnesium tablets may have other ingredients mixed in. “There are very few magnesium supplements that have been tested and verified in terms of knowing exactly what’s in them,” says Tarleton. She recommends always checking the bottle’s label to make sure the manufacturers have listed the amount of elemental magnesium (essentially, the volume of just the mineral itself) present in the pills. A health care professional is best suited to point you toward a good starting dosage—and weigh in on whether you should take magnesium at all, since supplements are not risk-free. “The big side effects of too much magnesium are diarrhea, upset stomach, and eventually nausea and throwing up,” says Tarleton. “Those are sort of the first signs” that you may be taking too much.

Like any sleep aid, it’s also best to use magnesium supplements sparingly, since their effects can weaken over time, Tarleton says. And before you start popping supplements, consider revamping your sleep hygiene and habits. “It’s much easier to take a supplement than to try to really take a hard look at what the reasons are that you’re not sleeping well to begin with.”