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Thinking of taking magnesium for sleep?

Magnesium for Sleep: Which Type and How Much

Reviewed · 5 sources · By Anthony Falcone

The short answer: Magnesium may help a little, but the evidence is thin. In small trials of older adults with insomnia, people fell asleep about 17 minutes faster than on placebo, and in the largest trial to date by its authors' count, 250 mg a day of magnesium bisglycinate eased insomnia scores slightly more than placebo over 4 weeks. No form has been shown to beat another for sleep, and the EU's upper limit for magnesium from supplements is 250 mg a day.1,2,5

Before you start

  • If you have kidney disease, talk to your doctor before taking magnesium. Trials behind this guide excluded people with kidney disease, so they tell you nothing about whether it is safe for you.1,2
  • If you take prescription medicines, ask your doctor or pharmacist first. The trials left out people on some of them, including loop diuretics and digoxin (a heart medicine), and drugs that affect sleep or mood such as antidepressants, beta-blockers and sedatives.1,2
  • If you are pregnant or breastfeeding, check with your doctor first; the recent trials excluded you.2,3
  • Loud snoring with pauses in breathing, falling asleep during the day, or poor sleep that lasts for months are reasons to see a doctor, not to try a supplement. For long-term insomnia, the authors of the bisglycinate trial name cognitive behavioural therapy for insomnia (CBT-I) as the most effective approach.2
  • 17 min faster to fall asleep than on placebo, pooled from 2 small trials in older adults (low certainty)1
  • 3.9 vs 2.3 points drop on the Insomnia Severity Index over 4 weeks: magnesium bisglycinate vs placebo2
  • 5 of 8 sleep studies in a 2024 systematic review reported some improvement4
  • 250 mg a day: the EU's upper limit for supplemental magnesium in adults5
  • 0 trials we found that compare one form of magnesium with another for sleep2,4

Does magnesium help you sleep?

A 2021 systematic review found only three randomised trials of magnesium against placebo in older adults with insomnia: 151 people in three countries, followed for 20 days to 8 weeks. Pooling two of them, people on magnesium fell asleep about 17 minutes faster. Total sleep time rose by about 16 minutes, but that result was not statistically significant.1

The reviewers rated all three trials at moderate to high risk of bias and the evidence as low to very low quality. Their verdict: the research is not good enough for doctors to make well-informed recommendations, although magnesium is cheap and widely available. They declared no competing interests.1

A broader 2024 systematic review of PubMed found 15 trials of magnesium for sleep or anxiety. Of the eight with sleep outcomes, five reported an improvement in at least one sleep measure, two found none and one was mixed. The authors warn that most of the studies were small and that they used different doses, forms and durations, and some added other active ingredients.4

What the newest trials found

The largest placebo-controlled trial so far by its authors' count, published in 2025, gave 155 healthy adults aged 18 to 65 who slept poorly either 250 mg of magnesium a day as bisglycinate or a placebo, for 4 weeks. Scores on the Insomnia Severity Index, a 0–28 questionnaire, fell by 3.9 points on magnesium and 2.3 on placebo. The difference was just significant and the effect small.2

Two things put that in proportion. Placebo helped too (scores fell 18% on placebo and 28% on magnesium), and at 4 weeks the magnesium group's average score was still in the range the authors call subthreshold insomnia, so supplementation alone is unlikely to end insomnia for many people. Other measures, including a single sleep-quality rating, daytime sleepiness, stress and mood, did not differ between the groups.2

A 6-week trial of magnesium L-threonate in 100 adults aged 18 to 45 with unsatisfying sleep gave 145 mg of elemental magnesium a day. Self-reported sleep-related impairment improved more than on placebo, but sleep disturbances and how restorative sleep felt did not, and a sleep-tracking ring showed no difference in sleep between the groups.3

Which type of magnesium is best for sleep?

Nobody has tested that yet. Each form has been tried in different people with different questionnaires: oxide and citrate in the older-adult trials, bisglycinate in the 2025 trial, and L-threonate in the 6-week trial. The bisglycinate trial's authors call for studies that compare forms, and the 2024 review says the most effective form and dose still need to be established.1,2,3,4

On absorption, the bisglycinate authors note that some studies suggest organic magnesium salts are absorbed slightly better than inorganic ones, but that direct comparisons are limited and earlier research suggests similar intestinal absorption across forms. For L-threonate, the European Food Safety Authority concluded in 2024 that magnesium is bioavailable from it.2,5

Bisglycinate also contains glycine: each day's dose in the 2025 trial included about 1.5 g. The authors think magnesium did most of the work but say glycine may have helped, so that trial can't tell the two apart.2

How much magnesium for sleep?

In the EU, the tolerable upper intake level for magnesium from supplements is 250 mg a day for adults. It was set from human studies in which magnesium supplements caused mild diarrhoea, with 250 mg a day as the highest intake without that effect. It comes on top of the magnesium you get from food, which it does not count.5

The limit was written for readily dissociable salts, such as magnesium chloride, sulphate, aspartate and lactate, and for magnesium oxide. When EFSA assessed magnesium L-threonate in 2024 and judged it safe, the maximum daily amount proposed also delivered 250 mg of magnesium. We use the same 250 mg ceiling for every form.5

That ceiling is also what the biggest trial used: 250 mg a day as bisglycinate. The L-threonate trial gave 145 mg a day. The three older-adult trials gave more than the 250 mg limit, so their doses are not a template to copy.2,3,1,5

When to take it

In the bisglycinate trial, people took their two capsules 30–60 minutes before bed, and most of the improvement appeared within the first 14 days. The L-threonate trial split the dose: one capsule in the morning and one about 2 hours before bed.2,3

No trial compared bedtime with morning dosing, so timing is a habit taken from the trials, not a tested rule.2,3

Side effects, and who seems to benefit most

Loose stools are the side effect to expect, and the EU limit is set to avoid them. In one of the older-adult trials every participant had soft stools. At 250 mg a day of bisglycinate, 2 adverse events were reported on magnesium and 7 on placebo; in the L-threonate trial, 10% on magnesium and 8% on placebo had a side effect possibly linked to the capsules.5,1,2,3

In an exploratory analysis of the bisglycinate trial, people who said they ate fewer magnesium-rich foods improved more. The question used was not validated, so this is a lead, not a finding. The 2024 review also suggests people low in magnesium may be the ones most likely to benefit.2,4

What to do with this

  • Expect a small effect at best: about 17 minutes faster to fall asleep in small, low-quality trials, and a slightly bigger drop in insomnia scores than placebo in the largest trial.1,2
  • If you try it, stay at or under 250 mg a day from supplements, the EU's upper limit; that is also the dose the biggest trial used.5,2
  • Pick the form you tolerate. Bisglycinate has the largest trial behind it, but no form has been shown to work better than another for sleep.2,4
  • Give it 2 to 4 weeks, taken 30–60 minutes before bed as in the bisglycinate trial, then judge whether it changed anything for you.2
  • If you still sleep badly, the rules of CBT-I, not a stronger supplement, are the next step; the bisglycinate trial's authors call it the most effective approach for long-term insomnia.2

How sure is this?

  • Most of the evidence is small. The review of older adults had three trials and 151 people, rated low to very low quality, and the sleep-onset result came from just 55 of them.1
  • Almost all outcomes are self-reported questionnaires, which respond strongly to placebo. The ring-measured sleep in the L-threonate trial did not differ from placebo, and the bisglycinate trial had no objective sleep measure.2,3
  • Industry ties: the L-threonate trial was funded by the company that supplied the product, and that company helped design the study. In the bisglycinate trial, funded by a university institute, one author runs a research company funded by supplement makers, and the capsules came from a supplement manufacturer.3,2
  • About 80% of the bisglycinate trial's participants were women (122 of 153), the trials lasted 20 days to 8 weeks, and they left out people with diagnosed sleep disorders such as sleep apnoea.2,1,3

Common questions

Does magnesium help you sleep?

A little, perhaps. Small trials in older adults found people fell asleep about 17 minutes faster than on placebo, and the largest trial found a small extra drop in insomnia scores, but the evidence is low quality.1,2

What is the best magnesium for sleep?

No trial has compared forms for sleep. Bisglycinate has the largest trial behind it (155 adults); citrate and oxide were used in older trials and L-threonate in one trial funded by the product's supplier.2,1,3

How much magnesium should I take for sleep?

No more than 250 mg a day from supplements: that is the EU's upper limit for adults, set to avoid diarrhoea, and the dose the largest sleep trial used.5,2

Magnesium glycinate vs citrate: which is better?

For sleep, nobody knows yet: they have never been tested against each other. Bisglycinate was studied in the largest recent trial and citrate in an older one; the trial authors say direct absorption comparisons between forms are limited.2,1

When should I take magnesium for sleep?

The largest trial had people take it 30–60 minutes before bed. No study has compared different times of day.2

Sources

  1. Mah J, Pitre T. Oral magnesium supplementation for insomnia in older adults: a Systematic Review & Meta-Analysis. BMC Complementary Medicine and Therapies, 2021. Meta-analysis. doi.org/10.1186/s12906-021-03297-z
  2. Schuster J, Cycelskij I, Lopresti A, Hahn A. Magnesium Bisglycinate Supplementation in Healthy Adults Reporting Poor Sleep: A Randomized, Placebo-Controlled Trial. Nature and Science of Sleep, 2025. Randomised trial. doi.org/10.2147/NSS.S524348
  3. Lopresti AL, Smith SJ. The effects of magnesium L-threonate (Magtein) on cognitive performance and sleep quality in adults: a randomised, double-blind, placebo-controlled trial. Frontiers in Nutrition, 2025. Randomised trial. doi.org/10.3389/fnut.2025.1729164
  4. Rawji A, Peltier MR, Mourtzanakis K, Awan S, Rana J, Pothen NJ, Afzal S. Examining the Effects of Supplemental Magnesium on Self-Reported Anxiety and Sleep Quality: A Systematic Review. Cureus, 2024. Review. doi.org/10.7759/cureus.59317
  5. EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA). Safety of magnesium l-threonate as a novel food pursuant to regulation (EU) 2015/2283 and bioavailability of magnesium from this source in the context of Directive 2002/46/EC. EFSA Journal, 2024. Official reference values. doi.org/10.2903/j.efsa.2024.8656

The Deep Sleep Protocol starts with the signs that need a doctor, then gives you the CBT-I rules sleep clinics use (a fixed wake time and stimulus control), a two-week sleep diary, an evening light and screen plan, and the honest evidence on magnesium and melatonin. The Supplement Stack Protocol adds a dosing and timing chart for magnesium alongside vitamin D3+K2, omega-3 and creatine. Deep Sleep Protocol · Supplement Stack Protocol

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