Magnesium has become one of the most popular sleep supplements, often marketed as a natural alternative to melatonin or prescription sleep aids. The evidence supports a real but more modest effect than the marketing suggests.
What magnesium does physiologically
Magnesium plays a role in regulating GABA, the primary inhibitory neurotransmitter in the nervous system, and in maintaining healthy melatonin production. It also supports muscle relaxation, which may explain reports of reduced restless legs and improved comfort at bedtime.
What the trials show
A number of small randomized controlled trials, particularly in older adults, have found modest improvements in sleep onset time and subjective sleep quality with magnesium supplementation, generally in the 200–400mg range taken in the evening. The effect appears most pronounced in people with a measurable magnesium deficiency, which is relatively common given modern dietary patterns.
Forms that matter
Magnesium glycinate and magnesium citrate are generally better absorbed and less likely to cause digestive upset than magnesium oxide, a cheaper but poorly absorbed form common in budget supplements.
Who is less likely to benefit
People who already get sufficient magnesium through diet — leafy greens, nuts, seeds, whole grains — are less likely to see a noticeable effect from supplementation, since the benefit is largely a matter of correcting a deficit.
The bottom line
Magnesium is a reasonable, low-risk option to try, particularly if your diet is low in magnesium-rich foods, but it’s a modest aid rather than a powerful sedative.
