Magnesium bisglycinate and reported poor sleep
A randomised, double-blind, placebo-controlled trial published in 2025.
Study design
The participants reported poor sleep. The daily amount describes the experiment, rather than a general dosing recommendation.
Measured result
Symptoms improved in both groups, slightly more with magnesium.
Reduction in Insomnia Severity Index after four weeks.
Questionnaire points; a larger reduction means fewer reported symptoms.
Small effect size: Cohen’s d = 0.2.
p = 0.049 for the difference in change. The effect size was small.
What this trial leaves open
- Whether a benefit continues beyond four weeks.
- Whether objective sleep measurements show the same pattern.
- Whether another magnesium form performs differently.
The tested product also supplied 1,523 mg glycine daily. There was no glycine-only group, so the separate contributions cannot be determined. Taking it 30–60 minutes before bed was the study protocol; the trial did not compare intake times.
Funding & disclosures. The paper reports funding by the Institute of Food and One Health, Leibniz University Hannover. Co-author Adrian Lopresti disclosed nutraceutical-industry research funding through his organisation and presentation honoraria. Methods and disclosures
Read the practical evidence guideWhat the trial means alongside the wider researchRead the 2026 reviewA broader view of the evidenceSources & further reading
Clinical papers, nutrition references and manufacturer labels are identified separately.