Does magnesium actually help sleep? Which form should I take?

Magnesium glycinate at 200–400 mg taken 60 minutes before sleep improves subjective sleep quality and modest objective sleep architecture improvements, particularly in men with magnesium deficiency (estimated at 50–60% of Western men on standard dietary assessments), through mechanisms involving NMDA receptor modulation and melatonin regulation (Abbasi et al., J Res Med Sci, 2012).

The form matters. Magnesium oxide (cheapest, most common supplement form) has poor bioavailability, roughly 4% absorption, and primarily produces a laxative effect at sleep-supporting doses. Magnesium glycinate (magnesium bound to glycine) and magnesium malate have bioavailability above 30%, cross the blood-brain barrier more readily, and the glycine component independently has sleep-supportive properties (reducing core body temperature and modulating NMDA glutamate receptors). Magnesium threonate (available as Magtein) is specifically marketed for cognitive effects and crosses the blood-brain barrier most readily, but costs more and the sleep-specific advantage over glycinate is not clearly established.

Honesty Scale: Promising (2) for magnesium glycinate sleep quality improvement in deficient populations. The evidence base is growing but lacks the large RCT confirmation that would push it to Solid (1).

What to do: Take 300 mg of magnesium glycinate 60 minutes before sleep. Do not take magnesium oxide, it is essentially inert for this purpose. Do not expect dramatic results if you are not deficient. Pair with sleep hygiene fundamentals rather than substituting magnesium for them.

For the full picture, read The Sleep Hygiene Deep Dive