Evidence Level
Magnesium's role in sleep is supported by both mechanistic and clinical evidence. Abbasi et al. (2012) demonstrated in a double-blind RCT that magnesium supplementation significantly improved subjective insomnia severity (ISI scores), sleep efficiency, sleep time, and melatonin concentration while reducing cortisol levels. Boyle et al. (2017) systematically reviewed 18 studies on magnesium and anxiety, finding a trend toward benefit especially in vulnerable populations. Held et al. (2002) showed magnesium administration increased slow-wave sleep (the most restorative sleep stage) in healthy subjects via EEG monitoring. The glycinate form is preferred for sleep/stress because glycine itself has been shown by Inagawa et al. (2006) to improve sleep quality through peripheral vasodilation and core body temperature reduction.