Source: NIH Office of Dietary Supplements — Magnesium — RDA 310–420 mg/day; supplemental studies for sleep/relaxation cluster around 300–400 mg elemental.
A highly absorbable, gentle form of an essential mineral involved in over 300 enzyme reactions.
Acts as a cofactor across energy, nerve and muscle systems; the glycine it's bound to is itself calming.
Magnesium bisglycinate cut Insomnia Severity Index scores more than placebo over 4 weeks, though the effect was small (Cohen's d ≈ 0.2).
Double-blind RCT · n=80 · 250 mg elemental Mg/day — 2025 — Nature & Science of Sleep (RCT)
Sleep-onset latency was ~17 min shorter with magnesium vs placebo in older adults — but all trials were low quality / high risk of bias.
Meta-analysis of 3 RCTs · n=151 · 320–500 mg/day — Mah & Pitre, 2021 — BMC Complement Med (meta-analysis)
Bottom line: A real but small benefit for sleep and relaxation, strongest in people who are older or genuinely low on magnesium. Trial quality is mediocre, so treat it as a gentle help, not a sleeping pill.
Glycinate is gentle, but too much magnesium (esp. oxide/citrate) causes loose stools. Supplemental upper limit is ~350 mg/day of elemental magnesium.
Anecdotes, not evidence, and not medical advice. Frequency labels are our read of forum sentiment, not a formal survey. Individual responses vary widely.
| Per serving | |
|---|---|
| Typical branded single-ingredient product | $0.50 |
| Bulk powder at the clinical dose (500g, $25.97) | $0.11 |
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Bulk price: $25.97/500g → Alt source: $21.99/250gEducational only — not medical advice. Grades and clinical doses are computed from public labels against sourced research (citations on the main site); prices last verified 2026-07-21. Expensive Powder has no sponsors; bulk links may earn an affiliate commission, which never affects a grade. Talk to a clinician before starting any supplement.