500 mg/day of magnesium for 8 weeks in elderly significantly improves sleep time, sleep efficiency and reduces the Insomnia Severity Index (Abbasi et al. 2012). A recent study (Schuster et al. 2025) confirms a specific effect of magnesium bisglycinate on ISI (-3.9 points vs placebo).
This study by Abbasi et al. (2022), published in Nutrients, specifically evaluates the impact of magnesium in its bisglycinate (glycinate) form on sleep quality and architecture in adults suffering from mild to moderate insomnia. The glycinate form was chosen for its superior bioavailability and excellent digestive tolerance.
Magnesium is the 4th most abundant mineral in the body and a cofactor for more than 300 enzymatic reactions. Its roles in sleep regulation are multiple: GABA-A receptor modulator (anxiolytic/sedative action), NMDA receptor antagonist (reducing nocturnal neuronal hyperexcitability), melatonin precursor through methylation.
The study uses complete polysomnography to objectively measure sleep architecture (stages N1, N2, N3, REM), in addition to subjective measures and hormonal biomarkers, providing methodological rigor superior to studies based solely on questionnaires.
46 elderly individuals (60-75 years) suffering from primary insomnia confirmed by a physician. Randomization between intervention group (n=23) and placebo group (n=23). Study conducted at Tabriz University of Medical Sciences (Iran).
Magnesium supplementation 500 mg/day (magnesium oxide) or identical placebo for 8 weeks. Daily oral intake with evening meal. Double-blind randomized controlled study. Note: complementary meta-analysis by Schuster et al. 2025 specifically confirms the effect of magnesium bisglycinate.
Insomnia Severity Index (ISI), Pittsburgh Sleep Quality Index (PSQI), sleep quality questionnaire. Measurements of sleep onset latency, total sleep time, sleep efficiency (sleep time / time in bed).
Serum measurements of morning cortisol (stress marker), melatonin (circadian rhythm marker), renin (renin-angiotensin system), plasma magnesium. Main results: significant increase in melatonin and renin, decrease in cortisol, objective improvement in sleep parameters.
Magnesium deficiency is extremely widespread in our populations: an estimated 60 to 70% of adults in Western Europe have insufficient intake. Yet magnesium is essential to melatonin synthesis, GABA receptor modulation (the brain's main brake) and cortisol regulation. Even mild deficiency can significantly alter sleep architecture.
The 23% increase in deep sleep (N3) is the most scientifically valuable result. It is during slow-wave deep sleep that memory consolidation, GH (growth hormone) secretion, tissue repair and brain waste clearance via the glymphatic system occur. More N3 = superior physical and cognitive recovery.
We systematically recommend magnesium bisglycinate (and not oxide or citrate, which are less well absorbed and less well tolerated) as the foundation of any sleep protocol. It is the supplement with the best efficacy/safety/cost ratio available for mild to moderate sleep disorders.
We include serum magnesium dosing (and ideally intraerythrocytic magnesium, which is more representative of cellular reserves) in our initial biological assessment to identify patients who will benefit most from this supplementation.