Question & Answer

Does ashwagandha help sleep and prevent nightmares?

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The Evidence

  • Ashwagandha is a herbal medicine derived from a small, evergreen shrub that grows in parts of India, the Middle East and Africa. It is sometimes called Indian ginseng or Indian winter cherry.
  • The root and leaves have been used in Indian traditional medicine for thousands of years for various purposes, including pain, inflammation, brain function, anxiety, stress and male infertility.
  • We were asked if it can help people sleep, and if it can prevent nightmares in menopausal women.
  • We didn’t find any information about nightmares during menopause or otherwise.
  • We found two systematic reviews about ashwagandha and sleep.
    • The first review was of moderate quality and included two small trials, one with people with insomnia and one with healthy people. One study was a randomised trial, meaning it compared one group who took the herb to another who did not. The second study followed only one group of people, so the improvements in sleep could have been down to chance. Both studies reported that taking ashwagandha improved sleep.
    • The second review was high quality and included five trials; two in people who were described as ‘stressed’; two in people with insomnia and one in healthy adults. They found a small improvement in sleep in those taking ashwagandha, especially in those with insomnia.
  • We also found five randomised trials about ashwagandha and sleep. Four of these were included in the reviews above. The fifth trial involved 60 college students. Those taking ashwagandha reported that their sleep improved compared with those not taking it.
  • Ashwagandha seems to help improve sleep, but there are a few problems with the research that we found about it.
    • Firstly, the studies used different strengths and types of ashwagandha, so it’s hard to compare them. We would need larger randomised trials to be sure.
    • Secondly, the studies were quite short in duration and the consideration of potential side effects was limited, so we don’t know the long-term positive or negative effects of taking it.

  Guidelines and recommendations

  • We didn’t find any guidelines or recommendations about ashwagandha.

Things to Remember

  • Look out for treatment effects that are based on small studies with few people.
  • If somebody got better after using a treatment, it doesn’t necessarily mean that the treatment made them better, it could have happened by chance.


  • Lead Researcher: Dr. Paula Byrne, Senior post-doctoral researcher, iHealthFacts, Evidence Synthesis Ireland and Cochrane Ireland, College of Medicine, Nursing and Health Sciences, University of Galway.
  • Reviewed by: Dr. Kayleigh Kew, Freelance researcher in evidence synthesis methods and technology, UK
  • Topic advisor: Dr. Sinéad Lydon, Associate Professor, Discipline of General Practice, School of Medicine, University of Galway.
  • 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.