Magnesium for Sleep: How Much, Which Form and What the Studies Show
TPBy the TrustedPurchaseReview Editorial Team
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The short answer
Adults need 310 to 420 mg of magnesium a day from food and supplements combined, and NIH sets the upper limit for magnesium from supplements at 350 mg a day. For sleep, the best review we found pooled three small trials in older adults with insomnia: magnesium helped them fall asleep about 17 minutes faster than placebo, but the evidence was rated low to very low. Forms that dissolve well, such as citrate, are absorbed better than oxide. Too much from supplements mainly causes diarrhea.
Magnesium is one of the most popular supplements sold for sleep. We read the NIH Office of Dietary Supplements fact sheet on magnesium and a 2021 systematic review on magnesium and insomnia. This guide is general information, not medical advice. If you have ongoing trouble sleeping, talk to a doctor.
How Much Magnesium You Need
| Age | Men | Women |
|---|---|---|
| 19 to 30 | 400 mg | 310 mg |
| 31 to 50 | 420 mg | 320 mg |
| 51 and older | 420 mg | 320 mg |
These are NIH’s Recommended Dietary Allowances, and they count food and supplements together. Good food sources include green leafy vegetables, legumes, nuts, seeds and whole grains. NIH notes that about 30% to 40% of the magnesium in food is absorbed, and that 48% of Americans get less magnesium from food and drinks than the average requirement for their age.
The 350 mg Supplement Limit
Supplements and food are counted differently
NIH sets the Tolerable Upper Intake Level for magnesium from supplements and medicines at 350 mg a day for adults. The limit does not apply to food, because the kidneys remove extra magnesium from food in healthy people. High doses from supplements often cause diarrhea, nausea and cramps, and very large doses from laxatives and antacids, typically over 5,000 mg a day, have caused magnesium toxicity.
Some products go above this limit, including one we reviewed. If a label gives more than 350 mg of elemental magnesium per serving, consider taking part of the serving and ask your doctor before taking the full amount.
Does Magnesium Help You Sleep?
A 2021 systematic review and meta-analysis in BMC Complementary Medicine and Therapies looked for randomized trials of oral magnesium for insomnia in older adults. It found three, with 151 participants in three countries.
| Outcome | Result compared with placebo |
|---|---|
| Time to fall asleep | About 17 minutes shorter, statistically significant |
| Total sleep time | About 16 minutes longer, not statistically significant |
| Quality of evidence | Low to very low; all trials at moderate to high risk of bias |
The authors concluded that the research is not good enough for doctors to make firm recommendations, but that because magnesium is cheap and widely available, the trials may support trying it for insomnia symptoms. The trials were in older adults, so the results may not apply to younger people.
What the evidence supports
- Possibly falling asleep somewhat faster, in older adults with insomnia
- Correcting a low intake, which is common
- A low cost, low risk thing to try at sensible doses
What it does not support
- Treating chronic insomnia on its own
- Doses above 350 mg a day from supplements
- Claims that magnesium “resets” your body clock
Which Form of Magnesium?
NIH says forms of magnesium that dissolve well in liquid are absorbed better, and that the aspartate, citrate, lactate and chloride forms tend to have higher bioavailability than magnesium oxide and magnesium sulfate. NIH also lists carbonate, chloride, gluconate and oxide as the forms most often reported to cause diarrhea.
Labels make this hard to compare. Many products list several forms inside a blend and print only the total. In that case you know the total magnesium but not how much comes from well absorbed forms. Our guide on what a proprietary blend hides explains why split amounts matter.
Who Is Most Likely to Run Low
NIH lists groups at higher risk of low magnesium: people with gastrointestinal diseases, people with type 2 diabetes, people with alcohol dependence and older adults. Older adults tend to eat less magnesium, absorb less from the gut and lose more in urine. Long term use of some drugs, such as loop and thiazide diuretics and proton pump inhibitors for more than a year, can also lower magnesium levels.
Medication Interactions
- Osteoporosis drugs. Magnesium can reduce absorption of oral bisphosphonates such as alendronate. NIH advises taking them at least 2 hours apart.
- Antibiotics. Tetracyclines and quinolones such as doxycycline and ciprofloxacin should be taken at least 2 hours before or 4 to 6 hours after a magnesium supplement.
- Kidney disease. Because the kidneys remove excess magnesium, people with kidney disease should only take magnesium supplements with a doctor’s advice.
Magnesium in Products We Reviewed
| Product | Magnesium per serving | Compared with the 350 mg limit |
|---|---|---|
| BIOptimizers Magnesium Breakthrough | 500 mg from 7 forms, amounts per form not listed | 150 mg above; one capsule gives about 250 mg |
We will add more magnesium products to this table as we review them.
Label Checklist
- Elemental magnesium in mg. Look for the elemental amount, not the weight of the whole compound. Magnesium compounds weigh more than the magnesium they contain: Magnesium Breakthrough, for example, uses 1,701 mg of magnesium compounds to deliver 500 mg of elemental magnesium.
- Total from all products. Add up every supplement and antacid or laxative you take that contains magnesium, and compare with 350 mg.
- The forms and their amounts. Citrate, aspartate, lactate and chloride tend to absorb better than oxide. Split amounts let you see what you are paying for.
- Subscription terms. Some magnesium products, including one we reviewed, are sold only as monthly subscriptions. Read the checkout before you pay.
FAQ
How much magnesium should I take for sleep?
Does magnesium really help you sleep?
What is the best form of magnesium?
Can I take too much magnesium?
When should I take magnesium?
Who should not take magnesium supplements?
Sources
- NIH Office of Dietary Supplements: Magnesium, fact sheet for health professionals. Source for the recommended intakes, upper limits, food sources and absorption, intake data, groups at risk, side effects, forms and interactions.
- Mah J, Pitre T. Oral magnesium supplementation for insomnia in older adults: a systematic review and meta-analysis. BMC Complementary Medicine and Therapies, 2021.
- TrustedPurchaseReview review of Magnesium Breakthrough, with label details as published by the brand.
About the editorial team
Written by the TrustedPurchaseReview editorial team. We read official labels and sales pages and check them against published research and government sources. We do not buy or test the products ourselves. We earn affiliate commissions on some links, and ratings are not for sale.
Questions or corrections? Contact us.
This guide is informational and not medical advice. Talk to your doctor about ongoing sleep problems and before taking any supplement.