Magnesium
Glycinate or citrate (not oxide)
Moderate
Some good studies, not many repeats
Moderate: meta-analysis of 3 RCTs (n = 151) graded low quality by the authors; observational data stronger than trials. Bisglycinate RCTs in 2025 improved subjective sleep.
In older adults with insomnia, it cut the time to fall asleep by about 17 minutes. It works best for people who get little magnesium from food.
In older adults with insomnia, magnesium shortened the time to fall asleep by about 17 minutes. Outside that group the trials are few and small, so we grade it moderate: a cheap, safe bet if your diet is low in magnesium, and probably a placebo if it isn't.
Magnesium is a cofactor for GABA receptors and blocks NMDA excitatory signalling; deficiency raises sympathetic tone.
Low dietary intake, older adults, restless-legs-type complaints. Glycinate or citrate; avoid oxide. Caution in kidney disease.
We compare each effect with how much that number normally swings from one night to the next. An effect smaller than the swing is real, but you will not see it in a week of data.
- Sleep onset latencyProbably visibleeffect: 17.36 minnormal swing: ±20 min
- Total sleep timeToo small to seeeffect: 16.06 minnormal swing: ±50 min
What to buy
- ✓'Elemental magnesium' clearly stated (200–400 mg)
- ✓Glycinate/bisglycinate or citrate
- ✓Chelated, third-party tested
- ✕Magnesium oxide (poorly absorbed)
- ✕'Magnesium complex' blends hiding the oxide share
- · Diarrhea at higher doses (form-dependent).
- · Caution in kidney disease.
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Two tablets are 200 mg of elemental magnesium as a glycinate–lysinate chelate, four are 400 mg — the label states the elemental figure, which is the one that matters. Best tolerated form, and the glycine carries its own sleep benefit.
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Powder lets you titrate the dose upward until you find your own tolerance point, and mix it with glycine in the same glass.
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Citrate is cheaper and absorbs well, with twenty-five thousand ratings behind it. It loosens stools at higher doses — that is the trade against glycinate.
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See all on AmazonEvery result, next to the line that means no effect
Each diamond is a study's best estimate. The thin line shows how sure the study was: the shorter the line, the more certain the result.
- Sleep onset latencymin · Mah 2021−17.4−27.3 … −7.44
- Total sleep timemin · Mah 2021+16.1−5.99 … +38.1
Each unit gets its own scale, so numbers are never mixed on one line. When a study gave no range, we leave it blank instead of inventing one.
2 studies over 1 years
The studies
- 1.Oral magnesium supplementation for insomnia in older adults: a systematic review & meta-analysisBMC Complementary Medicine and Therapies · 2021 · meta-analysis · 3 experiments · n = 151
Sleep onset latency −17.36 min; total sleep +16 min (not significant); low-quality evidence.
- 2.The role of magnesium in sleep health: a systematic reviewSleep Medicine Reviews (review) · 2022 · systematic review
Observational association with sleep quality; RCT evidence weak and uncertain.
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