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In this article
- Key points
- Magnesium and sleep: what’s the question?
- What kinds of studies are there?
- What did the magnesium bisglycinate study show?
- What about magnesium L-threonate?
- What do the studies show when taken together?
- Which claims are authorised for magnesium?
- Frequently asked questions about magnesium and sleep
- Sources
At a glance
- The studies don’t tell us which magnesium is best for sleep. They used different compounds, amounts and durations, and they don’t give a ranking of the forms1.
- A review published in 2026 rates the strength of the evidence on magnesium and sleep as low to very low1.
- In recent studies with magnesium bisglycinate and magnesium L-threonate, some individual measures came out better than with a placebo, and others didn’t2,3.
- There’s no authorised health claim relating to sleep for magnesium. One example of an authorised claim is ‘Magnesium contributes to normal functioning of the nervous system’.
Magnesium and sleep: what’s the question?
Many people take magnesium with sleep in mind1. Researchers have spent years looking at whether it actually changes sleep, and the answer is more cautious than some popular guides suggest. This article explains who was studied, what was measured and what the results were.
What kinds of studies are there?
A 2023 review analysed nine studies with a total of 7,582 adults4. They included observational studies, which only record associations, and randomised studies, in which some participants were given magnesium and others a placebo4.
The observational studies found an association between magnesium status and sleep quality, for example sleep duration and daytime sleepiness. The controlled studies, on the other hand, produced contradictory results4. The authors call for larger studies lasting longer than twelve weeks4.
This difference matters: an association doesn’t mean that magnesium is the cause. People with a high magnesium intake may eat differently overall, and that can affect sleep too. How to read studies like these is explained in our article on understanding the evidence.
What did the magnesium bisglycinate study show?
A 2025 study included 155 adults aged 18 to 65 who rated their own sleep as poor. For four weeks, they took either 250 mg of magnesium as bisglycinate or a placebo daily, 30 to 60 minutes before going to bed2. The study was randomised and double-blind, and it was funded by the university institute where it was carried out2.
The main outcome measure was a standardised sleep questionnaire, alongside questionnaires on wellbeing2. After four weeks, the questionnaire score had fallen by 3.9 points in the magnesium group and by 2.3 points in the placebo group. A lower score means that participants rated their sleep as better2.
The difference was only just statistically significant, and the authors describe it as small. The other questionnaires showed no differences2. In an exploratory additional analysis, the difference was larger in participants with a low magnesium intake from their diet. All the results are based on self-reports; there were no objective sleep measurements2.
What about magnesium L-threonate?
A 2024 study included 80 adults aged 35 to 55 who were dissatisfied with their sleep. For 21 days, they took either 1 g of magnesium L-threonate or a placebo daily, two hours before going to bed3. The gram refers to the whole compound, which contained about 75 mg of magnesium. Alongside several questionnaires, participants wore a ring that records sleep data3.
With threonate, the ring’s readings for deep sleep and REM sleep, among others, were higher than with the placebo, as were participants’ reports of mood, energy and daytime alertness3. On the sleep questionnaire that was also used in the bisglycinate study, both groups improved3. The study was funded by a company that three of the six authors worked for. It was also short, at three weeks3.
What do the studies show when taken together?
A 2026 review analysed twelve randomised studies in which magnesium was given on its own1. The participants, magnesium compounds, amounts, durations and measurement methods varied widely. The results were inconsistent, whether the researchers looked at questionnaires, brain-wave measurements (EEG) or sleep-tracker data1.
The authors rate the strength of the evidence as low to very low. For some individual self-reported measures, they consider modest benefits possible for some adults. In their view, however, larger and carefully designed studies are needed before general recommendations can be made1.
Good to know: In sleep studies, the way sleep is measured matters. Questionnaires capture how participants experience their sleep, while devices record it. The two approaches didn’t always lead to the same result, and devices weren’t used in every study1,2.
Which claims are authorised for magnesium?
In the EU, the effects of nutrients may only be described using health claims that have been checked and authorised. For magnesium, these include three: ‘Magnesium contributes to normal functioning of the nervous system’, ‘Magnesium contributes to normal psychological function’ and ‘Magnesium contributes to a reduction of tiredness and fatigue’. A claim about sleep isn’t one of them.
If you’d like to take magnesium as a supplement, look for a form you tolerate well, one that’s easy to take, and a suitable amount, rather than big promises. You’ll find an overview of the forms, from citrate to liposomal, in our comparison of magnesium forms. At Melinava, we use phospholipids from European sunflowers for our liposomal products.
Frequently asked questions about magnesium and sleep
Which magnesium is good for sleep?
The studies don’t give a ranking. Magnesium bisglycinate and magnesium L-threonate were among the forms studied, each against a placebo and not against each other2,3. Which form suits you depends more on how well you tolerate it and on your habits.
How long before bed should you take magnesium?
In the two studies described here, participants took magnesium 30 to 60 minutes and two hours before bed respectively2,3. These studies didn’t compare different times of taking it. There’s more on the time of day in our article on taking magnesium in the morning or evening. Do not exceed the recommended daily amount.
Why take magnesium before bed?
Many people associate magnesium with the evening and with sleep. But the studies so far don’t reliably show whether it changes sleep, and the evidence is rated low to very low1. There’s no authorised health claim relating to sleep for magnesium.
Sources
- Lopresti AL, Smith SJ, Drummond PD (2026). Magnesium Supplementation for Sleep in Adults: A Systematic Review of Randomized Controlled Trials. Journal of Dietary Supplements 23(5):553-581. DOI
- Schuster J, Cycelskij I, Lopresti A, Hahn A (2025). Magnesium Bisglycinate Supplementation in Healthy Adults Reporting Poor Sleep: A Randomized, Placebo-Controlled Trial. Nature and Science of Sleep 17:2027-2040. DOI
- Hausenblas HA, Lynch T, Hooper S, Shrestha A, Rosendale D, Gu J (2024). Magnesium-L-threonate improves sleep quality and daytime functioning in adults with self-reported sleep problems: A randomized controlled trial. Sleep Medicine: X 8:100121. DOI
- Arab A, Rafie N, Amani R, Shirani F (2023). The Role of Magnesium in Sleep Health: a Systematic Review of Available Literature. Biological Trace Element Research 201(1):121-128. DOI
This article is for general information only and should not replace medical advice. Food supplements are not a substitute for a balanced and varied diet and a healthy lifestyle.
Written by
Melinava Editorial Team