Protocol
Magnesium bisglycinate 250 mg elemental at bedtime
One randomized trial of the glycinate form: 155 adults with poor sleep took magnesium bisglycinate providing 250 mg elemental magnesium or placebo An inactive substitute made to look like the real treatment, so participants cannot tell which one they received. 30 to 60 minutes before bed for 4 weeks; the Insomnia Severity Index fell 3.9 points against 2.3 on placebo (p = 0.049, effect size How large a difference the treatment made, as distinct from whether the difference could be detected at all. 0.2), with no difference on other outcomes (Schuster 2025; PMID PubMed ID: the permanent number the US National Library of Medicine gives a published paper. Each one links to that paper's record on PubMed. 40918053).
Grade C: human trials exist, but they are small, mixed or not yet repeated. This is not a finding that it does not work. How to read a grade →
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How this letter has changedLatest: October 2026 · Corrected.
The record claimed multiple randomized trials improved sleep onset while citing one pooled analysis of three small trials of other salts (Mah et al., 2021; PMID 33865376), asserted a GABA and melatonin mechanism as settled, and carried a not-replicated flag beside pooled evidence. The one randomized trial of the glycinate form (Schuster et al., Nat Sci Sleep, 2025; PMID 40918053; 155 adults, 250 mg elemental, borderline positive on insomnia severity) is now the basis, with its glycine co-dose stated; the null citrate trial (Nielsen et al., 2010; PMID 21199787), the positive older-adult trial (Abbasi et al., 2012; PMID 23853635) and the 2026 systematic review A review that searches for every study on a question using a method set in advance, then assesses them together. concluding the evidence does not support magnesium for insomnia (Lopresti et al., 2026; PMID 42661485) are added. The written letter attaches to the dose and form studied, so the name moves from 300 to 400 mg to the 250 mg that was tested. C unchanged. Applied the written grade definition under the editor's standing instruction of October 2026 (Arnold Sandlow, D.C.).PMID 21199787 PMID 23853635 PMID 33865376 PMID 40918053 PMID 42661485
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This protocol is magnesium glycinate giving 250 mg of magnesium at bedtime. In one study, 155 adults with poor sleep took it for 4 weeks. Their insomnia scores improved a little more than with a dummy pill, but the gap was small. Other sleep measures did not differ. No one has repeated the study.
One randomized trial of the glycinate form: 155 adults with poor sleep took magnesium bisglycinate providing 250 mg elemental magnesium or placebo 30 to 60 minutes before bed for 4 weeks; the Insomnia Severity Index fell 3.9 points against 2.3 on placebo (p = 0.049, effect size 0.2), with no difference on other outcomes (Schuster 2025; PMID 40918053). Each dose also delivered about 1.5 g of glycine, itself studied for sleep, so the effect cannot be attributed to magnesium alone. Trials of other magnesium salts are small and mixed, and a 2026 systematic review of 12 trials rated the evidence inconsistent and low to very low certainty (Lopresti 2026; PMID 42661485). The protocol is named for the dose and form the one glycinate trial used; the earlier name, 300 to 400 mg, matched no glycinate trial.
Why this gradeGrade C, small or unreplicated trials. The reasoning, and what the grade does not cover.
Grade C on self-reported insomnia severity in adults with poor sleep, resting on one trial of the glycinate form: 155 adults took magnesium bisglycinate providing 250 mg elemental magnesium before bed for 4 weeks, and the Insomnia Severity Index fell 3.9 points against 2.3 on placebo, just significant with a small effect size and no difference on other outcomes (Schuster et al., 2025; PMID 40918053). A single borderline positive trial is C. The bisglycinate also delivered about 1.5 g of glycine a day, itself studied for sleep, so the result cannot be attributed to magnesium alone. Trials of other salts are small and mixed, positive in 46 older adults (Abbasi et al., 2012; PMID 23853635), null against placebo in 100 (Nielsen et al., 2010; PMID 21199787), pooled as low quality (Mah et al., 2021; PMID 33865376), and the 2026 systematic review of 12 trials rates the evidence inconsistent and low to very low certainty (Lopresti et al., 2026; PMID 42661485). Renamed in October 2026 from 300 to 400 mg, which no glycinate trial tested, to the studied 250 mg.
WHAT THIS GRADE DOES NOT COVERdoses of 300 to 400 mg of the glycinate form, which are untested; objectively measured sleep, where the pooled evidence is inconsistent; insomnia as a disorder diagnosed clinically, since the trial enrolled self-reported poor sleepers; and a mechanism on GABA or melatonin pathways, which the earlier description asserted and no cited trial measured.
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The evidence, in fullFive papers, each linked to its PubMed record.
Schuster et al. (Nat Sci Sleep, 2025; PMID 40918053): randomized double-blind Neither the participants nor the people assessing them know who received the real treatment until the trial ends. trial, 155 adults aged 18 to 65 with self-reported poor sleep, magnesium bisglycinate 250 mg elemental daily or placebo for 4 weeks; Insomnia Severity Index 3.9 points lower against 2.3 on placebo (p = 0.049, Cohen's d 0.2), no difference on other measures; the senior author directs a contract research organization funded by supplement companies. Other salts: Mah et al. (BMC Complement Med Ther, 2021; PMID 33865376), systematic review of oral magnesium for insomnia in older adults, three small trials, sleep onset latency about 17 minutes shorter and total sleep time not significantly changed, low to very low quality, with a 2024 erratum on PubMed. Abbasi et al. (J Res Med Sci, 2012; PMID 23853635): 46 older adults, 500 mg magnesium for 8 weeks, insomnia scores better than placebo, a different salt. Nielsen et al. (Magnes Res, 2010; PMID 21199787): 100 adults aged 51 to 85 with poor sleep, magnesium citrate 320 mg/day for 7 weeks; sleep quality improved equally on magnesium and placebo. Lopresti et al. (J Diet Suppl, 2026; PMID 42661485): systematic review of 12 randomized trials of magnesium alone for sleep; findings inconsistent across self-report, EEG and actigraphy, certainty low to very low, and the authors conclude the evidence does not support magnesium as a routine insomnia treatment. Grade C: one small, borderline, self-reported positive trial of the glycinate form, with mixed trials of other salts.
The Insomnia Severity Index or a sleep diary at baseline and 4 weeks, which is what the glycinate trial measured. Serum magnesium if deficiency is suspected.
Evidence notes: meta-analysis A study that pools the numbers from several trials into one combined estimate.
Endpoint The outcome a trial measures to decide whether the treatment worked, such as heart attacks, blood pressure or a symptom score. graded: Self-reported insomnia severity in adults with poor sleep (self_report)
Last reviewed: July 2026
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