Lying awake at 3am, staring at the ceiling? You are not alone. Magnesium has become one of the most popular supplements for sleep. So does it work, which type should you buy, and how much should you take?
Why magnesium matters
Magnesium is a mineral that helps more than 300 processes in the body run smoothly (National Institutes of Health, n.d.). It helps turn food into energy and supports healthy bones (NHS, n.d.a). Adults need about 300 mg a day (men) or 270 mg a day (women), which most people can get from foods such as spinach, nuts and wholemeal bread (NHS, n.d.a).
How might it help sleep?
Researchers think magnesium may support sleep in three ways, though most of this comes from laboratory research:
- Calming the brain: it helps a "calming" brain chemical called GABA do its job.
- Relaxing muscles: calcium helps muscles tighten, and magnesium helps them relax.
- Supporting the body clock: it may play a part in making melatonin, the hormone that tells your body it is time to sleep.
What the research shows
The honest answer is: a little, for some people.
- A review of three small trials in older adults found magnesium helped people fall asleep about 17 minutes faster, but did not significantly increase total sleep time. The authors rated the evidence as low quality (Mah and Pitre, 2021).
- A 2025 trial of 155 adults with poor sleep found 250 mg a day of magnesium bisglycinate for four weeks modestly improved insomnia scores compared with a placebo. People who ate less magnesium in their diet seemed to benefit most (Schuster et al., 2025).
Key insight
Magnesium is not a sleeping pill. It may give a small nudge, especially if your diet is low in magnesium, but it will not fix sleep problems caused by anxiety, pain, sleep apnoea or other health conditions.
Which type should you choose?
| Type | Good points | Downsides |
|---|---|---|
| Glycinate (bisglycinate) | Used in the 2025 sleep trial; usually gentle on the stomach | Often more expensive |
| Citrate | Well absorbed and affordable (National Institutes of Health, n.d.) | Can have a laxative effect |
| Oxide | Cheap | Poorly absorbed: about 4% in one study (Firoz and Graber, 2001) |
How much and when?
- Check the label for "elemental" magnesium. This is the amount of actual magnesium, not the weight of the whole compound.
- Start with 200 to 250 mg a day. The NHS says 400 mg or less a day from supplements is unlikely to cause harm, while higher doses can cause diarrhoea (NHS, n.d.a).
- Take it 30 to 60 minutes before bed as part of a wind-down routine.
- Give it 2 to 4 weeks, then decide whether it is helping.
⚠️ Check with a pharmacist first if you:
- have kidney disease, as your body may not clear extra magnesium
- take bisphosphonates such as alendronic acid, as magnesium can stop them being absorbed, so doses need spacing apart
- take tetracycline or quinolone antibiotics, for the same reason
- take any other regular medicines (National Institutes of Health, n.d.).
When to see your GP
See a GP if you have had trouble sleeping for months, or if it is making daily life hard to cope with. The main treatment the NHS recommends is cognitive behavioural therapy for insomnia (CBT-I), available face to face or online. Sleeping pills are now rarely prescribed (NHS, n.d.b).
The bottom line
If you are tired of being tired, magnesium is a low-risk, affordable thing to try alongside good sleep habits, as long as it is safe with your other medicines. Choose glycinate, keep to 200 to 250 mg of elemental magnesium, and keep your expectations realistic.
References
Firoz, M. and Graber, M. (2001) 'Bioavailability of US commercial magnesium preparations', Magnesium Research, 14(4), pp. 257–262. Available at: https://pubmed.ncbi.nlm.nih.gov/11794633/
Mah, J. and Pitre, T. (2021) 'Oral magnesium supplementation for insomnia in older adults: a systematic review and meta-analysis', BMC Complementary Medicine and Therapies, 21, p. 125. Available at: https://link.springer.com/article/10.1186/s12906-021-03297-z
National Institutes of Health (n.d.) Magnesium: fact sheet for health professionals. Office of Dietary Supplements. Available at: https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/
NHS (n.d.a) Others – vitamins and minerals (magnesium). Available at: https://www.nhs.uk/conditions/vitamins-and-minerals/others/
NHS (n.d.b) Insomnia. Available at: https://www.nhs.uk/conditions/insomnia/
Schuster, J. et al. (2025) 'Magnesium bisglycinate supplementation in healthy adults reporting poor sleep: a randomized, placebo-controlled trial', Nature and Science of Sleep, 17, pp. 2027–2040. Available at: https://doi.org/10.2147/NSS.S524348
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Important medical disclaimer
The content provided in this blog post is for educational and informational purposes only and does not constitute professional medical advice, diagnosis, or treatment. Always seek the advice of your GP, psychiatrist or another qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website. Never start, stop or change a prescribed medicine without speaking to your prescriber first.
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