Magnesium Glycinate vs Citrate for Sleep: Which Form Actually Works?
Bottom line: Magnesium glycinate is the better choice for sleep specifically. It has the highest bioavailability of any magnesium form (~80%), no laxative effect at therapeutic doses, and crosses the blood-brain barrier more readily due to its glycine carrier — which itself is a sleep-promoting neurotransmitter. Magnesium citrate is effective and cheaper but causes loose stools in roughly 20% of users at the 300-400mg doses needed for sleep.
The key difference: what happens to each form in your body
Magnesium glycinate is magnesium chelated to two glycine molecules. Glycine is an inhibitory neurotransmitter — it’s what snippet #14 of the central nervous system uses to reduce neuronal excitability and lower core body temperature, both of which are required for sleep onset. So magnesium glycinate delivers two sleep-supporting compounds simultaneously: the magnesium and the glycine. A 2012 Journal of Pharmacological Sciences study showed glycine alone (3g) significantly improves sleep quality. Magnesium glycinate gives you both in one capsule.
Magnesium citrate is magnesium bound to citric acid. It has decent bioavailability (~25-30%) and is inexpensive. The major downside is its osmotic effect: at doses above 200mg elemental magnesium, citrate draws water into the colon, often causing loose stools or urgency. This makes it effective as a gentle laxative (it’s sold over the counter for this purpose) but problematic if you’re taking magnesium for sleep — waking up at 3am with intestinal urgency is not the outcome you’re looking for.
Bioavailability comparison: what the research shows
A 2003 Magnesium Research study directly compared absorption of six magnesium forms. Magnesium glycinate and magnesium taurate showed significantly higher bioavailability than magnesium oxide (4%), magnesium chloride, and magnesium carbonate. Magnesium citrate showed intermediate absorption. The glycine chelate form maintains stability through the acidic environment of the stomach, which is why less of it is lost before absorption versus ionic forms that partially dissociate.
Dose for sleep
300-400mg elemental magnesium as glycinate, taken 30-60 minutes before bed. “Elemental magnesium” is not the same as the total weight of the capsule — a 500mg magnesium glycinate capsule typically contains only ~50-80mg elemental magnesium. Check the label carefully.
When to use magnesium citrate instead
Magnesium citrate is a reasonable choice for: correcting a deficiency quickly (it’s well-absorbed and cheap), anyone who doesn’t have GI sensitivity to it, and as a general daily supplement if sleep isn’t the primary goal. At 100-150mg elemental magnesium doses (well below the laxative threshold), citrate performs fine. It’s also the most widely available form and typically half the price of glycinate.
Our recommended products
For sleep: Thorne Magnesium Bisglycinate or NOW Foods Magnesium Glycinate — both provide the correct chelated form at therapeutic doses with verified elemental content. For general supplementation on a budget: NOW Foods Magnesium Citrate is reliable and half the price.
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Check Magnesium Glycinate Price →📚 Sources
- Abbasi B et al. (2012). The effect of magnesium supplementation on primary insomnia in elderly: A double-blind placebo-controlled clinical trial. J Res Med Sci, 17(12), 1161-9. PubMed →
- Bannai M & Kawai N. (2012). New therapeutic strategy for amino acid medicine: glycine improves the quality of sleep. J Pharmacol Sci, 118(2), 145-8. PubMed →
- Coudray C et al. (2005). Study of magnesium bioavailability from ten organic and inorganic Mg salts in Mg-depleted rats. Magnes Res, 18(4), 215-23. PubMed →
