Magnesium glycinate is magnesium bound to glycine, also sold as magnesium bisglycinate. In the only sleep trial of this form, 155 adults who took 250 mg of magnesium a day for 4 weeks slept a little better than with placebo, but the effect was small. Adults should keep supplement magnesium at or under 350 mg a day, and people with kidney disease should ask a doctor first.
On this page
- What are magnesium glycinate benefits?
- Is magnesium bisglycinate the same as magnesium glycinate?
- Does magnesium glycinate help you sleep?
- Magnesium glycinate vs citrate: which one fits you?
- How much magnesium glycinate per day?
- What is the best time to take magnesium glycinate?
- What are magnesium glycinate side effects?
- What do doctors try first for insomnia?
- Is magnesium glycinate worth trying?
- FAQ
Magnesium glycinate is magnesium bound to the amino acid glycine, and most people buy it hoping for better sleep. For this guide we read the NIH magnesium fact sheet, two NCCIH pages on sleep, the only published sleep trial of this form, and three reviews of magnesium for sleep, using the method on our how we review page.[1][3][6]
In one 2025 trial, 155 adults who took 250 mg of magnesium a day as bisglycinate slept a little better than with placebo. Reviews rate the wider evidence for magnesium and sleep as low quality.[6][8]
| What it is | A supplement form of the mineral magnesium, bound to glycine. Labels also call it magnesium bisglycinate.[3][6] |
|---|---|
| Most common use | Sleep. Interest grew after magnesium spread on social media as a bedtime drink ingredient.[2] |
| Amount studied for sleep | 250 mg of elemental magnesium a day, taken 30 to 60 minutes before bed, for 4 weeks.[6] |
| Daily need from all sources | 310 to 420 mg for adults, depending on age and sex.[3] |
| Upper limit from supplements | 350 mg a day for adults, unless a clinician advises more.[1][3] |
| Best evidence | One small trial in poor sleepers. Reviews of magnesium for sleep rate the evidence low to very low.[6][7][8] |
| Who should check first | People with kidney disease and people taking certain antibiotics, bone drugs, diuretics or acid reducers.[3] |
What are magnesium glycinate benefits?
The main benefit of magnesium glycinate is that it supplies magnesium, a mineral the body uses in more than 300 enzyme systems. Those systems run muscle and nerve function, blood sugar control and blood pressure regulation. If your diet is low in magnesium, a supplement can help you reach the daily target.[3]
Low intake is common. National survey data show that 48% of Americans get less magnesium from food and drinks than they need.[3]
Most benefit claims you see online come from studies of magnesium in general, using other forms. Here is what the NIH says about the best-known ones:
- Sleep: very little research, and the studies are small and of low quality.[1]
- Blood pressure: supplements lower it only a little. A Cochrane review of 12 trials in 545 people found a 2.2 mmHg drop in diastolic pressure.[3]
- Migraine: the American Academy of Neurology and the American Headache Society call magnesium probably effective for migraine prevention, though the data are limited.[3]
- Blood sugar: the American Diabetes Association says there is not enough evidence to use magnesium for glucose control.[3]
- Bones: magnesium is needed for bone, but more research is needed on whether supplements help with osteoporosis.[3]
- Stress and anxiety: a review of 18 studies found a hint of benefit in anxious people, but the evidence quality was poor.[11]
None of these findings came from glycinate studies. They describe magnesium as a whole, and this form has not been tested for any of them.
Is magnesium bisglycinate the same as magnesium glycinate?
Yes. Magnesium bisglycinate and magnesium glycinate are two names for the same chelated compound, which combines magnesium with glycine. Brands use both names on their labels, and the 2025 sleep trial used the bisglycinate name for its capsules.[6]
What matters more is the amount of magnesium on the label, because most of a bisglycinate capsule’s weight is glycine. In the trial, each 893 mg capsule held only 125 mg of magnesium, about 14% by weight.[6]
That is why the NIH tells shoppers to read the Supplement Facts panel. It lists the elemental magnesium, the part your body counts, and not the weight of the whole compound.[3] Some products are “buffered” blends that mix glycinate with other forms, so the share of each form can differ from brand to brand.
Does magnesium glycinate help you sleep?
Magnesium glycinate may help a little: the one trial of this form found a small improvement in sleep scores after 4 weeks. Before that 2025 study, the authors noted, glycinate had not been tested for sleep at all.[6] Broader reviews of magnesium for sleep, using other forms, rate the evidence as low to very low certainty.[7][8]
In the trial, 155 healthy adults aged 18 to 65 who said they slept poorly took 250 mg of magnesium as bisglycinate or a placebo each night. Insomnia scores fell by 3.9 points with magnesium and 2.3 points with placebo. The researchers called the effect size small (Cohen’s d of 0.2). Most of the change came in the first 14 days.[6]
A 2026 review of 12 trials concluded that current evidence does not support oral magnesium as a routine treatment for insomnia.[8] NCCIH also says there is not enough rigorous evidence to know whether magnesium supplements work for sleep problems.[2]
| Study | Who and how long | Dose | Result |
|---|---|---|---|
| Schuster et al., 2025 (RCT)[6] | 155 adults with poor sleep, 4 weeks | 250 mg magnesium as bisglycinate | Insomnia score fell 3.9 vs 2.3 points with placebo; small effect |
| Mah and Pitre, 2021 (meta-analysis)[7] | 3 trials, 151 older adults | 320 to 729 mg as oxide or citrate | Fell asleep 17.36 minutes faster; total sleep gain of 16.06 minutes was not significant; low quality |
| Abbasi et al., 2012 (RCT)[9] | 46 older adults, 8 weeks | 500 mg as oxide | Insomnia scores improved; total sleep time did not change |
| Lopresti et al., 2026 (review)[8] | 12 trials in adults | Various forms | Certainty low to very low; not supported as a routine insomnia treatment |
The glycine half may play a part. A small study found that 3 grams of glycine before bed eased next-day tiredness in people short on sleep, though the authors worked for a company that sells glycine.[10] The glycinate trial delivered about 1,523 mg of glycine a day, about half that amount.[6] A co-author of the trial also runs a research firm funded by supplement makers, so read the result as one promising early study.
Magnesium glycinate vs citrate: which one fits you?
For sleep, no trial has compared magnesium glycinate with citrate, so neither has been shown to work better. The bigger difference is in the gut. Magnesium citrate is also sold as a saline laxative, used short term for occasional constipation, and it usually causes a bowel movement within 30 minutes to 6 hours.[12]
On absorption, the NIH says small studies found citrate, aspartate, lactate and chloride absorbed more completely than oxide and sulfate. Glycinate is not named either way, so claims that it is “the best absorbed form” go beyond the evidence.[3] The NIH also lists the forms most often linked to diarrhea as carbonate, chloride, gluconate and oxide. Glycinate is not on that list, and only 7% of people in its sleep trial reported any side effect.[3][6]
Use this table to match the form to your goal. Treat it as a starting point to talk over with a pharmacist.
| If your goal is | Form people usually consider | Why |
|---|---|---|
| Trying magnesium for sleep | Glycinate | The only form tested in a recent sleep trial of poor sleepers.[6] |
| Occasional constipation | Citrate | Sold as a saline laxative for short-term use, no more than 1 week without a doctor.[12] |
| Filling a dietary gap with fewer loose stools | Glycinate or citrate at a modest dose | Citrate absorbs well; glycinate is not among the forms most linked to diarrhea.[3] |
| You have kidney disease | None without your doctor | Weak kidneys cannot clear extra magnesium, which raises the risk of toxicity.[3] |
How much magnesium glycinate per day?
Most adults should keep magnesium from supplements, including glycinate, at or under 350 mg a day, the federal upper limit. The sleep trial used 250 mg of elemental magnesium, split into two capsules.[3][6] Magnesium from food does not count toward that limit, because healthy kidneys remove extra from food.[3]
Your total daily need from food plus supplements is set by age and sex:
| Group | Daily need (all sources) | Upper limit from supplements |
|---|---|---|
| Men 19 to 30 | 400 mg | 350 mg |
| Men 31 and older | 420 mg | 350 mg |
| Women 19 to 30 | 310 mg | 350 mg |
| Women 31 and older | 320 mg | 350 mg |
| Pregnant, 19 to 50 | 350 to 360 mg | 350 mg |
Source for all rows: NIH Office of Dietary Supplements.[3] Food can cover much of this. One ounce of pumpkin seeds has 156 mg, an ounce of almonds has 80 mg, and half a cup of boiled spinach has 78 mg.[3]
Is 400 mg of magnesium glycinate too much?
It depends on what the 400 mg refers to. If the label means 400 mg of the whole bisglycinate compound, the elemental magnesium may be closer to 56 mg, using the trial’s 14% ratio.[6] If it means 400 mg of elemental magnesium, that is above the 350 mg supplement limit and should be cleared with a clinician first.[3] Some migraine trials used up to 600 mg a day, but those were research settings and not a guide for dosing yourself.[3]
Are magnesium glycinate gummies a good option?
Gummies can work if you dislike capsules, but check the Supplement Facts panel for the elemental magnesium per serving.[3] Compare that number with the 250 mg used in the sleep trial before you assume a gummy matches it.[6] Count added sugar, too.
A quick label checklist
- Find the elemental magnesium per serving on the Supplement Facts panel, not the compound weight.[3]
- Add up magnesium from every supplement you take, including multivitamins and antacids, and stay at or under 350 mg.[3]
- Check whether the product is pure glycinate or a buffered blend with other forms.
- Look for third-party testing seals and skip any label that says it cures sleep problems. See how we check supplement labels.
- Bring the bottle to your pharmacist if you take any prescription medicine.[3][4]
What is the best time to take magnesium glycinate?
For sleep, the only trial of magnesium glycinate had people take it 30 to 60 minutes before bedtime. That is the one timing with data behind it.[6] No study we found compared morning with evening doses, so if you take it for a reason other than sleep, any steady time of day is a reasonable choice.
Timing matters more around medicines. The NIH advises taking magnesium at least 2 hours apart from bisphosphonate bone drugs. Tetracycline and quinolone antibiotics should be taken at least 2 hours before or 4 to 6 hours after magnesium.[3]
In the trial, most of the gain showed up within 14 days.[6] If your sleep has not changed after 4 weeks of a steady dose, more magnesium is unlikely to be the answer, and a talk with your doctor is a better next step.[4]
What are magnesium glycinate side effects?
The most common side effects of magnesium supplements are diarrhea, nausea and stomach cramps, mostly at high intakes. In the glycinate sleep trial, 93% of people reported no side effects at all, and there were fewer events with magnesium than with placebo.[1][6]
Very high intakes can cause low blood pressure, nausea, flushing and muscle weakness, and in extreme cases an irregular heartbeat or cardiac arrest.[1][3] This is rare and usually tied to very large doses, laxatives or antacids that contain magnesium, or kidney problems.[3]
Who should talk to a doctor first
- People with kidney disease or reduced kidney function.[3]
- People taking bisphosphonates, tetracycline or quinolone antibiotics, loop or thiazide diuretics, or proton pump inhibitors for a long time.[3]
- People who are pregnant or breastfeeding, who have their own daily targets.[3]
- Anyone who snores loudly, gasps at night or fights daytime sleepiness, since these can be signs of sleep apnea.[1]
See a doctor right away if you feel very weak, have trouble breathing, or notice an irregular heartbeat after taking magnesium.[3]
What do doctors try first for insomnia?
The first treatment doctors recommend for long-term insomnia is cognitive behavioral therapy for insomnia, called CBT-I. It is a 6 to 8 week program that changes the thoughts and habits that keep you awake, and NCCIH calls it the most strongly recommended treatment.[1][4]
Insomnia that lasts a month or longer is called chronic, and most chronic cases are a symptom or side effect of another problem, such as a medical condition, a medicine or another sleep disorder.[5] Treating that cause often helps more than any supplement.
Simple habits also help: a fixed bedtime and wake time, and no caffeine, nicotine or alcohol close to bed. NHLBI advises talking to your provider before using any dietary supplement for sleep.[4] A magnesium supplement can sit alongside this care, but it is not a replacement for it.
Is magnesium glycinate worth trying?
Magnesium glycinate is a reasonable, low-risk thing to try if you sleep poorly and stay under 350 mg a day from supplements. Expect a modest change at most, since the best study found a small effect and the wider research on magnesium and sleep is weak.[3][6][8]
For most people with ongoing sleep trouble, CBT-I and steady sleep habits are the better first step, because they have far stronger evidence. Use glycinate as an add-on, check the elemental dose on the label, and ask a pharmacist about your medicines. Browse more guides in our sleep and rest section and our supplement ingredient guides.[1][4]
Frequently asked questions
Can you take magnesium glycinate every night?
Many adults can, as long as total supplement magnesium stays at or under 350 mg a day. The sleep trial used a nightly dose for 4 weeks with few side effects. Longer use has not been studied, so check in with your doctor.
How long does magnesium glycinate take to work for sleep?
In the 2025 trial, most of the improvement showed up within the first 14 days and held steady through week 4. If nothing has changed after about a month, more magnesium is unlikely to help, and a doctor visit makes more sense.
Can I get enough magnesium from food instead?
Often, yes. One ounce of pumpkin seeds has 156 mg, an ounce of almonds has 80 mg and half a cup of boiled spinach has 78 mg. Leafy greens, beans, nuts, seeds and whole grains are the best sources.
Is magnesium glycinate safe during pregnancy?
Pregnant adults need 350 to 360 mg of magnesium a day from all sources, and the 350 mg supplement limit still applies. No sleep trial has studied glycinate in pregnancy, so ask your obstetric provider before starting it.
Does magnesium glycinate help with anxiety?
The evidence is thin. A review of 18 studies of magnesium in general found a hint of benefit in people prone to anxiety, but rated the evidence quality as poor. No trial has tested glycinate for anxiety, and it should never replace care.
Sources
- Sleep Disorders and Complementary Health Approaches. NCCIH, National Institutes of Health, 2024
- In the News: Magnesium Supplements for Sleep Disorders. NCCIH, National Institutes of Health, 2024
- Magnesium: Fact Sheet for Health Professionals. NIH Office of Dietary Supplements, updated 2026
- Insomnia: Treatment. NHLBI, National Institutes of Health
- Insomnia. MedlinePlus, National Library of Medicine
- Magnesium bisglycinate supplementation in healthy adults reporting poor sleep: a randomized, placebo-controlled trial. Schuster et al., Nature and Science of Sleep, 2025
- Oral magnesium supplementation for insomnia in older adults: a systematic review and meta-analysis. Mah and Pitre, BMC Complementary Medicine and Therapies, 2021
- Magnesium supplementation for sleep in adults: a systematic review of randomized controlled trials. Lopresti, Smith and Drummond, Journal of Dietary Supplements, 2026
- The effect of magnesium supplementation on primary insomnia in elderly: a double-blind placebo-controlled clinical trial. Abbasi et al., Journal of Research in Medical Sciences, 2012
- The effects of glycine on subjective daytime performance in partially sleep-restricted healthy volunteers. Bannai et al., Frontiers in Neurology, 2012
- The effects of magnesium supplementation on subjective anxiety and stress: a systematic review. Boyle, Lawton and Dye, Nutrients, 2017
- Magnesium Citrate. MedlinePlus Drug Information, National Library of Medicine
Maya Ellison is the Reviews Editor at The Well Brew, a slow, plain-language supplement review blog for everyday adults. Maya reads each label in full, sets every dose beside the amounts used in human studies, grades the research with sources such as the NIH Office of Dietary Supplements and NCCIH, and works out the real cost and refund fine print. Maya has no medical credentials and is not a doctor, dietitian, nurse or pharmacist. Reviews give pros, cons and who a product suits, never scores. How we review supplements.
This article is general information, not medical advice. Dietary supplements are not reviewed by the FDA for safety or effectiveness before they are sold. Talk to your doctor before you start any supplement, especially if you are pregnant, nursing, take medication or have a health condition.