500 mg/day of magnesium glycinate for 8 weeks: -17 min sleep onset latency, +23% deep sleep, ISI score improved by 6.2 points, Abbasi et al. 2022 study.
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 adults aged 65 and over with insomnia (ISI ≥ 8) and serum magnesium at the low end of normal range (0.7–0.85 mmol/L). Double-blind RCT. 23 vs 23. Exclusion: hypnotic treatment, kidney conditions, ongoing magnesium supplementation.
Capsules of magnesium bisglycinate 500 mg (corresponding to 100 mg of elemental magnesium) or identical placebo, taken 1 hour before bedtime, for 8 weeks. Magnesium serum measurement at D0, D28 and D56 to verify compliance and response.
Ambulatory polysomnographic recording (type III) at D0 and D56. Parameters: sleep efficiency, total sleep time, duration of each stage (N1, N2, N3/slow-wave deep sleep, REM), number of awakenings. Gold standard of objective sleep measurement.
Salivary melatonin at 9 p.m. and 11 p.m. (before and after intervention). Morning salivary cortisol (8 a.m.). Plasma renin and aldosterone (magnesium regulation). Intraerythrocytic magnesium for measurement of cellular reserves.
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.