Magnesium for Sleep: Which Type Actually Works?

Published February 2025 · 8 min read

There are at least 10 different forms of magnesium supplements. Most do nothing for sleep. One form stands out—and it gives you a double benefit. Here's how to choose.

Walk into any supplement store and you'll find a dozen magnesium products. Magnesium oxide, citrate, glycinate, threonate, taurate, malate... The labels all claim benefits, but they're not interchangeable.

For sleep specifically, the form you choose matters more than the dose. Here's why.

Why Magnesium Affects Sleep

Magnesium is involved in over 300 enzymatic reactions in your body, including several directly related to sleep:

GABA function. Magnesium binds to GABA receptors, enhancing this calming neurotransmitter's effects. Low magnesium = less effective GABA signaling = harder to relax.

Muscle relaxation. Magnesium regulates muscle contraction. Deficiency can cause restless legs, cramps, and tension that interfere with sleep.

Melatonin regulation. Magnesium is required for melatonin synthesis. Deficiency can actually impair your body's natural melatonin production.

Stress response. Magnesium modulates the HPA axis (your stress system). Chronic stress depletes magnesium, and low magnesium amplifies stress—a vicious cycle.

The problem is widespread. Modern diets are often low in magnesium (processed foods, depleted soils), while stress increases magnesium demand. Many people are functionally deficient without knowing it.

The Forms: A Quick Breakdown

Different magnesium forms have different absorption rates and effects. For sleep, this matters a lot.

Why Glycinate Is Best for Sleep

Magnesium glycinate combines magnesium with glycine, an amino acid. This pairing gives you two sleep-supporting compounds in one:

Glycinate is also one of the best-absorbed forms, meaning you get more benefit per milligram. And unlike citrate, it doesn't have laxative effects—a real consideration if you're taking it nightly.

What About Magnesium Threonate?

Magnesium threonate (Magtein) is marketed heavily for brain health. It does cross the blood-brain barrier more effectively than other forms, which theoretically could benefit sleep.

The downsides:

Cost. Threonate is significantly more expensive than glycinate—often 3-4x the price for similar magnesium content.

Lower elemental magnesium. Threonate supplements contain less actual magnesium per capsule, so you need to take more.

Less research for sleep specifically. The brain-health claims are better supported than the sleep claims.

If budget isn't a concern and you want the theoretical brain benefits, threonate is fine. But for pure sleep support, glycinate gives you more value—and you get the glycine bonus.

Avoid Magnesium Oxide

Magnesium oxide is the most common form in cheap supplements because it's inexpensive to produce. The problem: absorption is terrible—estimated at only 4%.

A 500mg magnesium oxide pill might deliver only 20mg of usable magnesium. You'd need to take huge doses to get any benefit, and at those doses, the main effect is laxative.

If your magnesium supplement is very cheap, check the form. It's probably oxide.

How Much to Take

Many people notice effects within the first few nights. However, if you've been deficient for a long time, it may take 1-2 weeks for levels to build up.

Signs You Might Be Deficient

Magnesium deficiency often goes undiagnosed because standard blood tests measure serum magnesium, which is tightly regulated and doesn't reflect total body stores. You can be functionally deficient with "normal" blood levels.

Common signs of magnesium deficiency:

• Muscle cramps or twitches
• Restless legs, especially at night
• Difficulty relaxing or "wired but tired" feeling
• Poor stress tolerance
• Headaches
• Sugar or chocolate cravings (chocolate is high in magnesium)
• Trouble falling or staying asleep

If you have several of these symptoms and your sleep is poor, magnesium supplementation is worth trying.

Combining Magnesium with Other Sleep Supplements

Magnesium works well in combination with other non-sedating sleep supports:

Avoid combining magnesium with large doses of calcium at the same time—they compete for absorption. If you take both, separate them by a few hours.

Best Magnesium Glycinate Products

For sleep support, we recommend:

NOW Foods Magnesium Glycinate — Good quality, reasonable price ($18 for 180 caps), reliable brand with GMP certification. Our budget pick.

Thorne Magnesium Bisglycinate — NSF certified (higher testing standard), good absorption, trusted brand. More expensive but verified quality.

Pure Encapsulations Magnesium Glycinate — Hypoallergenic, no fillers, pharmaceutical-grade. Best for sensitive individuals.

Avoid products that mix glycinate with oxide or citrate to pad the magnesium content—you lose the glycine benefits and absorption quality.

The Bottom Line

If you're looking for a melatonin alternative, magnesium glycinate is one of the easiest places to start. It's affordable, well-tolerated, and addresses a deficiency that many people have without realizing it.

The key is choosing the right form. Glycinate gives you both magnesium and glycine—two compounds that support sleep through different mechanisms. Avoid oxide, which is poorly absorbed and won't do much for sleep.

Unlike melatonin, magnesium doesn't cause tolerance. You can use it indefinitely without needing higher doses—and the benefits extend beyond sleep to stress response, muscle function, and overall health.