Question & Answer

Does taking magnesium supplements make a difference to sleep?

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The Evidence

  • It has been claimed that taking magnesium supplements improves the quality of sleep.
  • We looked for studies to find out whether or not magnesium supplements improve the quality of sleep.
  • We found three relevant, high-quality systematic reviews. However, while a systematic review might be of high quality (that is, it’s been done correctly), sometime the studies included in the review are of low quality. This is why, sometimes, as you’ll see below, you can have a high-quality review of low-quality studies.
  • The first systematic review reported that magnesium supplements improve sleep onset and improve insomnia symptoms. However, the results came from low or very low-quality studies.
  • The second systematic review looked at randomised controlled trials (5 RCTs) and observational studies (1 cohort study and 3 cross-sectional studies). The RCTs reported that magnesium supplements have an uncertain effect on sleep. The observational studies denoted that magnesium may improve sleep quality. However, observational studies cannot prove that something caused something else. This is because this type of study doesn’t compare two similar groups of people; one which takes magnesium and one which does not, making sure you’ve a fair comparison.
  • The third systematic review included two RCTs, which found no beneficial effect of magnesium supplements on sleep quality.
  • Overall, none of the systematic reviews we found could be certain that magnesium supplements improve sleep quality.
  • Further research is needed to figure this out.

Guidelines and recommendations

  • We searched several national and international organisations including WHO, CDC, ECDC, HSE, and HSPC for related guidelines and recommendations. We did not get any recommendations on the use of Magnesium supplements in relation to sleep quality.

Things to Remember

  • Just because one study shows that people who got a treatment did better or worse than those who did not, does not mean it’s the final answer.
  • If someone gets better after a treatment, it does not necessarily or always mean that the treatment made them better.
  • We can rarely be 100% certain about any claim.


  • Lead Researcher: Dr KM Saif-Ur-Rahman, Senior Research Methodologist, Evidence Synthesis Ireland and Cochrane Ireland, College of Medicine, Nursing and Health Sciences, University of Galway.
  • Reviewed by: Dr Paula Byrne, Senior post-doctoral researcher, iHealthFacts, Evidence Synthesis Ireland and Cochrane Ireland, College of Medicine, Nursing and Health Sciences, University of Galway.
  • Topic advisor: Prof Andrew Murphy, College of Medicine, Nursing and Health Sciences, University of Galway, Health Research Board Primary Care Clinical Trials Network Ireland and General Practitioner principal in a semi-rural setting.
  • Public and Patient advisor: Anne Daly, Public and Patient Involvement in research (PPI) advisor, PPI Ignite, University of Galway.
  • Journalist Advisor: Dr Claire O’Connell, PhD in cell biology, Masters in Science Communication. Contributor to The Irish Times, writing about health, science and innovation.

Conflict of Interest Statement: The authors have no financial or other conflicts of interest for this health claim summary.