← All supplements
Limited evidenceSleep & relaxation

Magnesium Glycinate

A well-absorbed, gentle-on-the-gut form of magnesium marketed for sleep and anxiety. The magnesium-for-sleep literature is small and low quality, and no trial has tested the glycinate form specifically against other forms.

Where to buy

View on iHerb

Ships to 180+ countries · welcome discount for new customers

Referral link — this site may earn a commission on purchases.

What the science says

  • Falling asleep faster Limited evidence

    A systematic review and meta-analysis pooled only three RCTs of oral magnesium in older adults with insomnia and found a reduction in time to fall asleep of roughly 17 minutes. The authors rated the certainty of the evidence as very low because the trials were small and at high risk of bias.

  • Anxiety and subjective sleep quality Limited evidence

    A systematic review of magnesium for self-reported anxiety and sleep quality found mostly small studies with inconsistent results, often using magnesium combined with other ingredients. No consistent effect emerged in people who are not magnesium deficient.

  • The glycinate form specifically Limited evidence

    Claims that glycinate is calmer or better absorbed than oxide or citrate rest on pharmacokinetic reasoning and a handful of comparative absorption studies, not on head-to-head sleep or anxiety trials. Its real practical advantage is causing less diarrhoea than magnesium oxide.

Dosage & safety

Studied doseTrials of oral magnesium for sleep used 320–500 mg elemental magnesium daily, taken in the evening. Check the label for elemental magnesium, not total compound weight — glycinate is heavy, so a 1000 mg capsule may supply only ~140 mg of magnesium.
SafetyGenerally well tolerated; loose stools are the main dose-limiting effect and are less common than with oxide or citrate. Magnesium reduces absorption of tetracycline and quinolone antibiotics, bisphosphonates and levothyroxine — separate by at least 2 hours. People with impaired kidney function should not supplement magnesium without medical supervision.

How to take it

TimingEvening, 30-60 minutes before bed, matching how the sleep trials dosed it.
With food?With food or a snack, which reduces the loose stools that are the main dose-limiting effect.
Worth knowingRead the elemental magnesium figure, not the capsule weight - glycinate is a heavy molecule, so a 1000 mg capsule may deliver only about 140 mg of magnesium.

Interactions

With medications

  • tetracycline and quinolone antibiotics

    Magnesium chelates these antibiotics in the gut and sharply reduces how much drug reaches the bloodstream. separate by at least 2 hours, taking the antibiotic first

  • levothyroxine

    Magnesium binds levothyroxine and lowers its absorption, which can undo a stable thyroid dose. separate by at least 4 hours - take levothyroxine on waking and magnesium in the evening

  • bisphosphonates such as alendronate

    Absorption of the bisphosphonate is markedly reduced. take the bisphosphonate on an empty stomach in the morning and magnesium at least 2 hours later

With other supplements

  • high-dose calcium taken in the same dose

    Large single doses of calcium and magnesium compete for the same intestinal transport. split them to different times of day if you take more than about 500 mg of either

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does magnesium glycinate help you sleep?

The evidence is limited. A meta-analysis of only three small trials of oral magnesium in older adults with insomnia found people fell asleep about 17 minutes faster, with very low certainty, and no trial has tested the glycinate form specifically.

Is magnesium glycinate better than other forms?

Magnesium glycinate's clear practical advantage is causing less diarrhoea than magnesium oxide. Claims that it is calmer or better absorbed rest on pharmacokinetic reasoning, not on head-to-head sleep or anxiety trials.

How much magnesium glycinate should I take for sleep?

Sleep trials used 320-500 mg of elemental magnesium daily in the evening. Read the elemental figure on the label, because magnesium glycinate is heavy: a 1000 mg capsule may supply only about 140 mg of magnesium.

Can I take magnesium glycinate with thyroid medication or antibiotics?

Magnesium glycinate reduces absorption of levothyroxine, tetracycline and quinolone antibiotics and bisphosphonates. Separate it by at least 4 hours from levothyroxine and at least 2 hours from the others, and avoid it with impaired kidney function unless supervised.

Scientific references

Related in Sleep & relaxation