Most people run a little low, the right form fixes sleep and cramps, and the wrong form just gives you the runs.
Magnesium is a mineral involved in hundreds of processes in the body, including muscle relaxation, nerve function, and sleep. A meaningful share of people don't get quite enough from food, and if you train hard, sweat a lot, or sleep poorly, topping up is one of the more sensible supplements you can add. The catch is that the form matters enormously — pick the wrong one and you get a laxative instead of a sleep aid.
This guide covers what magnesium does, why glycinate is usually the best form for sleep and recovery, the forms to avoid unless you actually want a laxative effect, and how to dose it without overdoing it. The short version: magnesium glycinate, 200-400 mg, in the evening.
What it is
Magnesium is an essential mineral your body can't make, so you get it from food (leafy greens, nuts, legumes, whole grains) or supplements. It plays a direct role in how muscles relax after they contract, how your nervous system winds down, and how well you sleep, which is why low intake often shows up as cramps, restlessness, or poor sleep quality.
Supplements come bound to different 'carriers', and that carrier decides both how well it absorbs and what it does to your gut. Magnesium glycinate (bound to the amino acid glycine) is gentle on the stomach and calming, making it the go-to for sleep and recovery. Magnesium citrate absorbs well but has a stronger laxative effect. Magnesium oxide is cheap, poorly absorbed, and mostly used as a laxative.
What the evidence supports
- Supports muscle relaxation, which can help with the cramps and twitchiness that hard training or heavy sweating can bring on.
- Glycinate in particular is associated with calmer evenings and better sleep quality for people who run low.
- Plays a role in normal nerve function and a steady, relaxed nervous system.
- Involved in energy production and hundreds of enzyme reactions, so adequacy supports general function.
- Citrate forms can also help with occasional constipation, if that's what you're after.
How to use it
Dose: 200-400 mg of elemental magnesium from glycinate in the evening. Check the label for 'elemental' magnesium, since the total powder weight is much higher than the actual magnesium content.
Timing: Take it 30-60 minutes before bed for the sleep and wind-down benefit. It can be taken with or without food.
More is not better — very high doses (especially citrate or oxide) cause loose stools and cramping. Magnesium can interact with some medications, including certain antibiotics. This is general guidance, not medical advice; check with your doctor if you have kidney issues or take prescription medication.
What to look for
- Choose magnesium glycinate (sometimes labelled bisglycinate) for sleep and recovery with minimal laxative effect.
- Read the 'elemental magnesium' amount per serving, not just the total compound weight.
- Avoid magnesium oxide unless you specifically want a cheap laxative — it's poorly absorbed.
- Prefer a clean single-ingredient product without unnecessary proprietary 'sleep blends' stacked on top.
FAQ
Which magnesium is best for sleep?
Magnesium glycinate. It's well absorbed, gentle on the stomach, and the glycine it's bound to is itself mildly calming, which is why it's the usual pick for evening use.
Why did magnesium give me diarrhea?
You probably took citrate or oxide, or too high a dose. Those forms pull water into the gut. Switch to glycinate and stay in the 200-400 mg elemental range and it usually resolves.
Can I just get magnesium from food?
Ideally, yes — greens, nuts, seeds, legumes, and whole grains are great sources. A supplement is simply an easy top-up if your diet runs low or your needs are higher from heavy training.