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Is it just us or does magnesium feel like the “cool girl” of the minerals? Constipated? Take magnesium to help you poop. Dealing with muscle cramps? Try magnesium. Need to chill the F out? Again, magnesium.
The mineral (which is also an electrolyte) is kind of a big deal—and for good reason. “Magnesium is necessary for over 300 chemical reactions in our bodies,” says Marissa Meshulam, RD, a registered dietitian and founder of the private practice MPM Nutrition. “Some of magnesium’s main roles include muscle and nerve function, heartbeat regulation, blood sugar management, digestion, and bone health.”
Magnesium supplements are also commonly recommended for sleep, but the form you take matters.
Here’s what experts have to say about taking a magnesium supplement for a better night’s rest.
How does magnesium affect sleep?
You might first think of melatonin as the darling of the sleep supplement world. When it comes to melatonin vs. magnesium, the hormone melatonin directly affects your circadian rhythm, while magnesium’s relationship to sleep is a little less straightforward. “The main effect is that magnesium relaxes your mind, body, and muscles,” says Brian Chen, MD, a sleep medicine doctor at Cleveland Clinic’s Sleep Disorders Center.
Magnesium may promote restfulness in a few different ways. According to an April 2022 study in Sleep, the mineral activates GABA—a neurotransmitter that calms the central nervous system. It also suppresses calcium levels in muscle cells, which in turn helps muscles relax. That’s why it’s used to improve both symptoms and sleep quality in those with restless legs syndrome, per a December 2022 randomized controlled trial in BMC Complementary Medicine and Therapies.
“Magnesium has been shown to reduce cortisol, our stress hormone, and therefore makes us feel more relaxed and ready for sleep,” Meshulam adds. Oh, and it plays a role in melatonin production, hence why some sleep supplements bundle magnesium and melatonin together.
Despite all those connections, Dr. Chen says the verdict is still out on whether there’s night-to-night effectiveness of taking magnesium for better sleep. “Large-scale population studies haven’t shown that magnesium truly helps people fall asleep much faster on a regular basis, so it’s very individualized in terms of whether it works,” he says.
An April 2021 paper in BMC Complementary Medicine and Therapies reported that, on average, older adults with insomnia fell asleep 17 minutes sooner when supplementing with magnesium compared to those who received placebos. Yet even the study authors noted this finding was based on unclear evidence, and they labeled the association between magnesium intake and improved sleep symptoms “uncertain.” (Womp womp.)
Long story short: Magnesium can certainly help you feel more zen, but it’s unlikely to knock you out. The good news? There’s little risk in adding a magnesium supplement to your evening routine for relaxation. Just make sure you’re choosing the proper type of magnesium, as there are several.
Which type of magnesium is best for sleep?
Magnesium glycinate supplements are your best bet if you’re using the mineral to wind down at night. Dr. Chen says this form is better absorbed than alternatives like magnesium citrate and magnesium oxide—which act as laxatives and are often recommended to treat constipation. (Real talk: Accidentally taking magnesium oxide could have the opposite of your intended effect if it keeps you on the toilet all night.)
And don’t forget that plenty of foods have this essential mineral, too. Black beans, spinach, avocado, almonds, pumpkin seeds, and dark chocolate (you’re welcome) are all good sources of magnesium, per the National Institutes of Health.
Dosage and timing of magnesium for sleep
“I recommend starting at 200 milligrams of magnesium glycinate and taking it about 30 minutes before getting ready to sleep,” Meshulam says.
Magnesium glycinate supplements are generally well-tolerated and safe, but it’s a good idea to run them by your doctor if you’ve been diagnosed with kidney or liver disease, Dr. Chen says.
And more magnesium isn’t always better. Dr. Chen recommends capping magnesium supplementation to 400 milligrams per night if you’re using it to help you relax. “Too much magnesium can cause irregular heartbeat, low blood pressure, and muscle weakness,” Meshulam says. Also, if your supplement gives you diarrhea, you’re probably taking too much.
Other sleep tips
If you’re chronically tired, work with your doctor to investigate other possible causes before hopping on a magnesium supplement. “I recommend checking iron, vitamin D, and vitamin B12 levels first to rule out other nutrient deficiencies in people who feel fatigued,” Dr. Chen says.
Don’t sleep on (pun intended) a solid nighttime routine, either. Meshulam recommends simple sleep hygiene tips like keeping your bedroom dark and cool, avoiding caffeine after noon, and finishing eating at least two to three hours before getting in bed. “Limiting blue light exposure [from screens] and finding ways to relax, such as meditating, reading, or using lavender essential oils, is also helpful,” Meshulam says.
Best magnesium supplements for sleep to try
Before trying any new supplements, it’s always a good idea to run them by your healthcare provider first. Once they’ve given their “okay,” try buying products from reputable brands—because vitamins and supplements aren’t very closely regulated by the FDA.
“I recommend looking for a third-party tested supplement,” Meshulam says. “This way you know you’re actually getting what the brand says you are.” Look for products that follow Current Good Manufacturing Practices (cGMPs) and are USP- or NSF-certified, which indicates they’ve been third-party tested. You’ll usually see these distinctions on a product’s label or website.
Two picks Meshulam loves? Thorne’s magnesium bisglycinate powder ($47 on Amazon) and Pure Encapsulations’ magnesium glycinate capsules ($26 on Amazon).
While magnesium gummies are also a thing, you’re better off choosing an unflavored powder or capsule to avoid unnecessary added sugars and food dyes, especially before bed. And remember: Magnesium isn’t a sleeping medication (like Ambien, for example). It could improve sleep onset by helping you wind down, but it hasn’t been proven to keep you zonked throughout the night.
“Taking magnesium before bed may help relax your body and brain so you can slip off to sleep more easily,” Dr. Chen says. “But it might not have a lasting effect through the night.”