But here's something you might not know: There's actually another supplement out there that could also help you get some sleep—in fact, your body might even be deficient in it already: magnesium.

The mineral plays an important role in tons of bodily functions: metabolism, blood sugar regulation, bone health, and nerve and muscle function, among other things. And, no surprise, it plays a crucial role in sleep, too. Here, a sleep doctor weighs in on what you need to know about magnesium, and why you might want to start using that instead of other sleep remedies (yep, melatonin, I'm looking at you).

So wait, magnesium really can help you sleep?

According to some evidence, yes, confirms W. Christopher Winter, M.D., author of The Sleep Solution and a board-certified sleep specialist at Charlottesville Neurology and Sleep Medicine in Virginia.

For one, magnesium is an important player in many of the steps that allow you to take protein and convert it into the chemicals that help you feel sleepy, explains Dr. Winter. It also helps calm the nervous system down, helping it work more efficiently, and plays a role in muscle relaxation and nerve function, he says. (That's why magnesium is often a supplement docs use to help people with managing symptoms of restless leg syndrome, says Dr. Winter.) 

Magnesium also helps the body maintain levels of GABA (a.k.a., gamma-aminobutyric acid), a neurotransmitter that Dr. Winter notes is responsible for "turning off" wakefulness. Magnesium can also help the body's dopamine levels rise, which can improve your mood says Dr. Winter. And if migraines are keeping you up, well, they can help alleviate those too, according to the American Migraine Foundation. 

That means magnesium is safe to take for sleep?

In essence, yes, says Dr. Winter. According to the National Institutes of Health's Office on Dietary Supplements, the recommended dietary allowance (RDA) for magnesium when used for sleep or general health is 310 milligrams a day. Dr. Winter backs this up by saying that a good, moderate dose of magnesium is about 100 to 350 milligrams, daily. That dose should be void of any side effects. 

But if you go above that 350-milligram threshold, you’ll likely notice some diarrhea. In fact, milk of magnesia can be loaded in magnesium (one tablespoon might have 500mg)—hence why it’s used as a laxative. And very large doses of magnesium—like upwards of 5,000 milligrams a day—can lead to magnesium toxicity, which can include heartbeat irregularities or even cardiac arrest. But again, that's in extremely high doses. 

But it's still worth noting that you can (and should) try to get a solid amount of magnesium from your diet so you don't have to turn to a supplement, says Dr. Winter. That means adding more foods like almonds, spinach, soy milk, peanut butter, and avocado, which are all good sources of magnesium, to your meals before you go out and buy a supplement.

The bottom line: Popping a magnesium supplement once in a while is fine if you're having a hard time falling asleep, says Dr. Winter, but if it's a chronic issue, it's time to check in with your doc.