sleep · 1 min read
Best magnesium for sleep: glycinate, citrate or threonate
The best magnesium for sleep is glycinate: well absorbed, gentle on the gut, and the only form with its own placebo-controlled sleep trial. Oxide absorbs worst. Four common forms compared. Four common forms compared.
Written by Lifebar Desk · Checked against the sources listed below
Published 28 Aug 2026
Key takeaways
- Magnesium glycinate is the usual choice for sleep, high absorption, minimal laxative effect.
- Magnesium oxide is roughly 4% bioavailable and mostly acts on the bowel.
- Supplemental magnesium above 350 mg of elemental magnesium a day commonly causes diarrhoea.
Most magnesium supplements differ in one respect that matters: how much of the mineral survives your digestive tract.
The comparison
| Form | Absorption | Best for | Gut effect |
|---|---|---|---|
| Glycinate | High | Sleep, general repletion | Minimal |
| Citrate | Moderate-high | Repletion, constipation | Mildly laxative |
| Malate | Moderate | Daytime use, fatigue | Low |
| Oxide | Very low (~4%) | Constipation only | Strongly laxative |
| Threonate | Moderate | Cognition claims | Low |
Reading the label properly
Compound weight is not mineral weight. Magnesium glycinate is roughly 14% elemental magnesium; citrate about 16%; oxide about 60% but barely absorbed. A "500 mg" capsule can deliver anywhere from 60 to 300 mg of usable magnesium.
The dose that causes trouble
The tolerable upper intake for supplemental magnesium is 350 mg of elemental magnesium a day for adults. Above that, diarrhoea is the common and self-limiting result. Food magnesium has no such limit because absorption self-regulates.
Who should not supplement
Chronic kidney disease impairs magnesium clearance and makes accumulation a real risk. Magnesium also interacts with some antibiotics and bisphosphonates, which need separating by a few hours.
For what magnesium does and does not do for sleep itself, see does magnesium help you sleep.
Frequently asked
Does the label number mean elemental magnesium?
Not always. A 1,000 mg magnesium citrate capsule may contain only about 160 mg of elemental magnesium. Check the supplement facts panel.
Is magnesium threonate worth the price?
The brain-penetration claim comes from animal work and small human trials on cognition, not sleep. It costs several times more than glycinate.
Sources
Educational content, talk to your clinician before changing treatment.
