Magnesium and Sleep: Helpful or Overhyped?

Patrick Elliott, BSc, MPH
Jan 28
9 min read

Health influencers across the internet promote magnesium supplementation for better sleep. But does the scientific evidence back this claim up?

Introduction

Magnesium is an essential mineral; our body cannot make it and we must consume it through food and/or supplements. Magnesium plays an important role in a variety of bodily processes, from energy production, to muscle contraction, to blood pressure regulation, and many more (1). In addition to its critical roles in the body, greater magnesium intakes (from diet and supplements) are associated with better sleep quality and duration in observational studies (2,3), hinting at a possible role for magnesium in supporting sleep.

There are a number of possible explanations for magnesium’s role in supporting sleep. Magnesium, along with minerals like manganese and calcium, helps the brain send calming signals (4), which may support relaxation and better sleep. In addition, magnesium works to promote muscle relaxation (5), and magnesium supplementation can decrease levels of cortisol (6,7), a stress hormone. Research in rats has also found that a deficiency of magnesium can lead to a reduction in melatonin (8)—a sleep-protective hormone.

While all of this sounds promising, to understand if magnesium supplementation improves sleep, we need to look at studies that demonstrate better sleep outcomes in those taking magnesium supplements compared to those who don’t. Because while it seems that magnesium certainly plays a role in supporting sleep, this does not necessarily mean that supplementing with magnesium is a sure-fire way to improve sleep quality and quantity.

Magnesium-rich foods include whole grains, certain fruits, green-leafy vegetables, and nuts/seeds.

Magnesium Supplementation Trials

In an analysis of three trials that compared magnesium or placebo supplementation in older adults with insomnia, those supplementing with magnesium for up to two months fell asleep 17 minutes quicker (on average) than those taking the placebo, and improved their total sleep time by 16 minutes (on average) (9). In another trial, this time in individuals with type 2 diabetes, those supplementing with a magnesium supplement for two months increased their melatonin levels and decreased their cortisol levels, but there were no significant differences in insomnia severity between those supplementing with magnesium and those taking a placebo pill (10).

In another study, where 31 middle-aged individuals with self-reported poor sleep quality consumed a magnesium supplement for two weeks, participants reported better sleep quality, and some objective measures of sleep quality were improved relative to those taking the placebo (11). In a similar study from the same research group, 80 individuals with self-reported sleep problems supplementing with a magnesium supplement likewise improved certain measures of sleep quality, as well as self-reported energy, daytime productivity, mood, and mental alertness relative to those taking a placebo (12).

Problems with the Evidence Base

In the aforementioned trials, the specific types of magnesium supplement taken ranged from magnesium oxide (9), to magnesium citrate (9), to magnesium chloride (11), to magnesium L-threonate (12). And in the study from Khalid et al. (10), the authors didn’t even report what type of magnesium supplement was used. This makes comparisons between studies very difficult because different forms of magnesium supplements contain different amounts of actual magnesium (known as elemental magnesium), and because absorption can vary between types of magnesium supplements.

Table 1. Elemental magnesium content of magnesium salts commonly used in magnesium supplements.

Magnesium salt type	Elemental magnesium content	Calculation
Magnesium oxide	~60%	24.3 g/mol (Mg) ÷ 40.3 g/mol (MgO) × 100 ≈ 60%
Magnesium chloride	~25.5%	24.3 g/mol (Mg) ÷ 95.2 g/mol (MgCl₂) × 100 ≈ 25.5%
Magnesium citrate	~16% (anhydrous form) ~12% (nonahydrate form)	Anhydrous: 72.9 g/mol (Mg₃) ÷ 451.1 g/mol × 100 ≈ 16.2% Nonahydrate form contains added water, reducing Mg %
Magnesium bisglycinate	~14%	24.3 g/mol (Mg) ÷ 174.4 g/mol (Mg(C₂H₄NO₂)₂) × 100 ≈ 14%
Magnesium L-threonate	~7–8%	24.3 g/mol (Mg) ÷ ~294–313 g/mol (hydration-dependent) × 100 ≈ 7–8%

Abbreviations: Mg: magnesium; O: oxygen; Cl: chloride, C: carbon; H: hydrogen; N: nitrogen.

Subscript numbers show how many atoms of each element are present, e.g., MgCl₂ = 1 magnesium + 2 chloride atoms. Atomic and molecular weights were derived from Pubchem.

For example, the 1,000 mg of magnesium L-threonate provided in one study translates to ~75 mg of elemental magnesium (12); the 1,000 mg of magnesium chloride provided in another study translates to ~255 mg of elemental magnesium (11); and the amount of magnesium given in the three trials of older adults with insomnia was between ~300–700 mg of elemental magnesium (9). With such a mix of doses and supplement types—as well as differences in study design and sleep measures—it is impossible to draw any conclusive conclusions about the effectiveness of magnesium in supporting sleep quantity and quality from this data.

Did you know?

The amount of elemental magnesium contained in various magnesium salts is calculated from basic chemistry, by comparing magnesium’s atomic weight to the salt’s total molecular weight. For example, magnesium oxide is ~60% magnesium because 24.3 of its 40.3 molecular-weight units come from magnesium.

What About Magnesium Bisglycinate?

Perhaps the most popular (and expensive) magnesium supplement on the market today is known as magnesium bisglycinate. This form of magnesium salt is said to be better absorbed than other magnesium salt types, and the additional glycine bound to the magnesium atom has been suggested to synergistically positively impact sleep given some previous research suggesting possible sleep improvement effects of glycine-only supplementation (13). Despite the hype, magnesium bisglycinate was only shown to increase brain levels of magnesium at a high dose (equivalent to 405 mg/70 kg individual) in a study on mice (14), and it is unclear whether magnesium bisglycinate is better absorbed relative to other forms in humans (15).

In a recent trial of 153 participants with sleep problems, those taking a magnesium bisglycinate supplement (containing 250 mg of elemental magnesium and 1,523 mg of glycine) 30–60 minutes before bed reported a significant improvement in insomnia symptoms compared to those taking a placebo (16). Despite experiencing an improvement, those taking the supplement still had poor sleep quality after using the supplement, with their sleep quality in the sub-threshold insomnia range (defined as a score of 8–14 on the Insomnia Severity Index) after 4 weeks (Figure 1) (16).

Magnesium bisglycinate improves Insomnia Index Severity vs. placebo in a 4 week trial; however differences are small in magnitude.

Figure 1. Change in insomnia symptoms severity, as measured by the Insomnia Severity Index, in the trial from Schuster et al. (16). While the difference was statistically significant, the effect size was small (reflected by a Cohen’s d of 0.2).

Believe it or not, but the trial discussed in this blog article on magnesium bisglycinate and sleep outcomes (16) is the only trial ever conducted in humans testing the impact of magnesium bisglycinate on sleep. Remember that next time you hear an influencer extolling its game-changing sleep benefits...

What Can We Conclude?

Given all the data presented in this article, here are my main takeaways:

There is limited evidence to suggest that magnesium supplementation improves sleep, and the limited data that is suggestive of a benefit is limited to specific populations (e.g., those with insomnia or very poor sleep).
Most benefits that have been reported in studies relate to subjective sleep measures, which is a limitation.
The range of supplementation types (e.g., oxide vs. citrate vs. bisglycinate, etc.) and doses of elemental magnesium given to participants makes it impossible to know what types and doses may be most effective for sleep.
It is possible that people with low dietary magnesium intake (from food) may experience a greater sleep benefit from supplementation (16); however, we need more trials in magnesium-depleted individuals to really understand if this is true or not.

Summary

If you’re a poor sleeper, there is no harm in trying a magnesium supplement, particularly if your diet is low in magnesium-rich foods (e.g., whole grains, nuts/seeds, green-leafy vegetables). However, the current data suggests it’s not a silver bullet, and I would first recommend trying to improve your sleep hygiene and avoid caffeine after lunchtime. To circle back to the title of this article, the data suggests that magnesium is overhyped for its sleep benefits, though it could be helpful for some people.

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Thanks for reading!

Patrick Elliott, BSc, MPH

Health and Nutrition Science Communication Officer at Training121

Email: patrickelliott@training121.com

Instagram: @just.health.info

References

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(2) Zhang Y, Chen C, Lu L, Knutson KL, Carnethon MR, Fly AD, Luo J, Haas DM, Shikany JM, Kahe K. Association of magnesium intake with sleep duration and sleep quality: findings from the CARDIA study. Sleep. 2022;45(4):zsab276. Available at: https://academic.oup.com/sleep/article/45/4/zsab276/6432454

(3) Arab A, Rafie N, Amani R, Shirani F. The Role of Magnesium in Sleep Health: a Systematic Review of Available Literature. Biol Trace Elem Res. 2023;201(1):121–28. Available at: https://link.springer.com/article/10.1007/s12011-022-03162-1

(4) He C, Wang B, Chen X, Xu J, Yang Y, Yuan M. The Mechanisms of Magnesium in Sleep Disorders. Nat Sci Sleep. 2025;17:2639–56. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC12535714/

(5) JENKINSON DH. The nature of the antagonism between calcium and magnesium ions at the neuromuscular junction. J Physiol. 1957;138(3):434–44. Available at: https://physoc.onlinelibrary.wiley.com/doi/abs/10.1113/jphysiol.1957.sp005860

(6) Held K, Antonijevic IA, Künzel H, Uhr M, Wetter TC, Golly IC, Steiger A, Murck H. Oral Mg(2+) supplementation reverses age-related neuroendocrine and sleep EEG changes in humans. Pharmacopsychiatry. 2002;35(4):135–43. Available at: https://www.thieme-connect.de/products/ejournals/abstract/10.1055/s-2002-33195

(7) Abbasi B, Kimiagar M, Sadeghniiat K, Shirazi MM, Hedayati M, Rashidkhani B. The effect of magnesium supplementation on primary insomnia in elderly: A double-blind placebo-controlled clinical trial. J Res Med Sci. 2012;17(12):1161–9. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC3703169/

(8) Billyard AJ, Eggett DL, Franz KB. Dietary magnesium deficiency decreases plasma melatonin in rats. Magnes Res. 2006;19(3):157–61. Available at: https://www.jle.com/fr/revues/mrh/e-docs/dietary_magnesium_deficiency_decreases_plasma_melatonin_in_rats_272226/article.phtml

(9) Mah J, Pitre T. Oral magnesium supplementation for insomnia in older adults: a Systematic Review & Meta-Analysis. BMC Complement Med Ther. 2021;21(1):125. Erratum in: BMC Complement Med Ther. 2024;24(1):418. Available at: https://bmccomplementmedtherapies.biomedcentral.com/articles/10.1186/s12906-021-03297-z

(10) Khalid S, Bashir S, Mehboob R, Anwar T, Ali M, Hashim M, Waseem H, Basharat S. Effects of magnesium and potassium supplementation on insomnia and sleep hormones in patients with diabetes mellitus. Front Endocrinol (Lausanne). 2024;15:1370733. Available at: https://www.frontiersin.org/journals/endocrinology/articles/10.3389/fendo.2024.1370733/full

(11) Breus MJ, Hooper S, Lynch T, Hausenblas HA. Effectiveness of Magnesium Supplementation on Sleep Quality and Mood for Adults with Poor Sleep Quality: A Randomized Double-Blind Placebo-Controlled Crossover Pilot Trial. Med Res Arch. 2024;12(7). Available at: https://esmed.org/MRA/mra/article/view/5410

(12) Hausenblas HA, Lynch T, Hooper S, Shrestha A, Rosendale D, Gu J. Magnesium-L-threonate improves sleep quality and daytime functioning in adults with self-reported sleep problems: A randomized controlled trial. Sleep Med X. 2024:17;8:100121. Available at: https://www.sciencedirect.com/science/article/pii/S2590142724000193

(13) Yamadera W, Inagawa K, Chiba S, Bannai M, Takahashi M, and Nakayama K. Glycine ingestion improves subjective sleep quality in human volunteers, correlating with polysomnographic changes. Sleep Biol Rhythms. 2007;5:126–31. Available at: https://onlinelibrary.wiley.com/doi/full/10.1111/j.1479-8425.2007.00262.x

(14) Ates M, Kizildag S, Yuksel O, Hosgorler F, Yuce Z, Guvendi G, Kandis S, Karakilic A, Koc B, Uysal N. Dose-Dependent Absorption Profile of Different Magnesium Compounds. Biol Trace Elem Res. 2019;192(2):244–51. Available at: https://link.springer.com/article/10.1007/s12011-019-01663-0

(15) Schuchardt JP, Hahn A. Intestinal Absorption and Factors Influencing Bioavailability of Magnesium-An Update. Curr Nutr Food Sci. 2017;13(4):260–78. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC5652077/

(16) Schuster J, Cycelskij I, Lopresti A, Hahn A. Magnesium Bisglycinate Supplementation in Healthy Adults Reporting Poor Sleep: A Randomized, Placebo-Controlled Trial. Nat Sci Sleep. 2025;17:2027–40. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC12412596/

Technical Terms

Essential: An essential nutrient is something your body needs to stay healthy but cannot make on its own. You have to get it from food or supplements. Examples include vitamins and minerals.

Cortisol: A hormone your body releases to help you respond to stress. It also plays a role in regulating energy, blood sugar, and inflammation.

Melatonin: A hormone your body naturally makes to help regulate your sleep–wake cycle. It’s often called the ‘sleep hormone’ because levels rise in the evening to signal that it’s time to wind down and get ready for sleep, and fall again in the morning when it’s time to wake up.

Statistical significance: This is a term to describe the likelihood of whether a finding in a study is a real finding, or if it is the result of chance. Statistical significance is denoted by a p-value, which is usually set at a significance (alpha) level of 0.05. This means that if a result is significant at this level (p≤0.05), we can say that the probability of getting a value as or more extreme than the observed value (under the assumption that the null hypothesis is true) is less than 5%. In other words, it is more likely that this finding is not the result of chance than if the p-value was >0.05 (although this is not always the case).

Effect size: In a study, an effect size describes how big or meaningful a result is, not just whether it exists. It helps answer the question: ‘Even if this effect is real, how much does it actually matter?’. Effect sizes can be calculated via various statistical methods, with common measures including Cohen’s d, Hedge’s g, and partial eta-squared (η2p).