Magnesium for Sleep: Does It Actually Work?

Magnesium is involved in more than 300 enzymatic reactions in the body, including the regulation of melatonin and the GABA pathway that helps calm the nervous system at night. That makes it a plausible sleep aid — but the evidence is more modest than the supplement aisle suggests.

What magnesium actually does for sleep

Clinical trials have found modest improvements in sleep onset and quality with magnesium supplementation, particularly in older adults with low baseline magnesium status. In otherwise well-nourished younger adults, the effect is smaller.

The best-studied forms for sleep are magnesium glycinate and magnesium L-threonate. Magnesium oxide (common and cheap in Canadian pharmacies) is poorly absorbed and is more useful as a laxative than a sleep aid.

How much to take — and when

Most sleep studies used 200–400 mg of elemental magnesium an hour before bed. Health Canada’s tolerable upper intake from supplements is 350 mg/day for adults.

Start at 200 mg; digestive side effects (loose stools) climb quickly past 400 mg, especially with magnesium citrate.

Food sources Canadians already eat

Canadian-grown pumpkin seeds (156 mg per ounce), almonds, spinach, black beans and dark chocolate all contribute. Hitting 320–420 mg/day from food alone is realistic for most Canadians who eat vegetables.

The bottom line

If you struggle with sleep and your diet is light on leafy greens, nuts and seeds, magnesium glycinate at 200–300 mg before bed is a cheap, low-risk experiment. Don’t expect miracles.

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