Due to its actions as an N-methyl-D-aspartate (NMDA) antagonist and a gamma-aminobutyric acid (GABA) agonist, magnesium is hypothesized to help regulate the sleep/wake cycle and thereby promote healthy sleep.[1][2] For this reason, magnesium is often promoted as a sleep-enhancing supplement, and some people use magnesium to treat insomnia and improve sleep quality and/or sleep duration. However, there is surprisingly little evidence to support its use.
Some evidence from animal studies shows that higher magnesium levels in specific sites in the brain are associated with better sleep quality.[3] Some evidence from observational studies in humans finds low serum magnesium concentrations in people with obstructive sleep apnea, a sleep disorder associated with sleep disturbances.[4] Meanwhile, other evidence from observational studies shows that higher magnesium intake is associated with better sleep quality.[5] However, these lines of evidence do not prove that magnesium helps with sleep.
Unfortunately, very few randomized controlled trials have assessed the effect of magnesium on sleep quality or sleep duration, and their outcomes are mixed.[6][7][8] Consequently, although recent systematic reviews and meta-analyses have found that supplemental magnesium may reduce sleep latency by approximately 17 minutes, they conclude that the quality of current evidence is insufficient to make well-informed recommendations and that larger randomized controlled trials are needed to remedy that issue.[1][9]