Does ashwagandha actually help with anxiety and sleep?

Like one in five U.S. adults, I live with anxiety. So when a YouTuber I follow claimed that a supplement called ashwagandha helped her feel calmer, I was curious.

Ashwagandha has been used in traditional Indian medicine for thousands of years, but its global popularity has recently soared thanks to TikTokers raving about its stress-busting and sleep-improving effects. 

“This comes up in my practice quite a bit,” says Dr. Jasmine Sawhne, a board-certified psychiatrist in California.

But what exactly is ashwagandha—and is the hype around it backed by science?

What is ashwagandha?

Ashwagandha (Withania somnifera) is a plant grown in Asia, Africa, and parts of Europe. Its name comes from the Sanskrit words ‘ashwa’ (horse) and ‘gandha’ (smell)—a nod to the wet-horse odor of the plant’s roots. You may also hear it called winter cherry or Indian ginseng, though it’s unrelated to true ginseng.

Most supplements are made from the plant’s root, though some contain both root and leaf extracts.

“In Ayurvedic medicine ashwagandha is known as a ‘rasayana’, which is a medicine used to enhance physical performance and re-vitalise the mind,” says Professor Jerome Sarris from the National Institute of Complementary Medicine (NICM) in Australia.  Ashwagandha and other rasayana medicines are natural products that fall under the broader category of ‘adaptogens’, substances believed to help the body adapt to stress.

What do studies show?

Some studies suggest that ashwagandha may help ease stress and anxiety. In clinical trials, participants who took ashwagandha for six to eight weeks reported feeling less stressed, anxious, and fatigued. In some cases, blood or saliva tests showed lower levels of cortisol, the body’s primary stress hormone.

There is also early evidence that ashwagandha may improve sleep. In some studies, people taking ashwagandha reported falling asleep faster, sleeping longer, and waking up less often during the night.

Still, results are far from conclusive. “These studies have largely been pilot trials with smaller sample sizes,” says Ashley Curtis, the director of the Cognition, Aging, Sleep, and Health Lab at the University of South Florida. “Higher quality evidence via larger-scale randomized placebo-controlled trials is needed to determine the clinical utility of the compound.”

How does it work?

Ashwagandha contains several plant compounds, including withanolides, which are thought to drive many of its effects. But early research suggests that other compounds may also play a role.

When the body faces stress, the hypothalamus, pituitary gland, and adrenal glands work together to release cortisol. “Ashwagandha appears to modulate the hypothalamic-pituitary-adrenal (HPA) axis, helping reduce chronic overactivation of the stress response,” says Dr. Jamey Maniscalco, a neuroscientist and wellness consultant. 

Animal studies and limited human data suggest that ashwagandha may also boost brain pathways that promote relaxation, he said. One of these involves GABA (gamma-aminobutyric acid), a chemical that quiets nerve activity, helping the brain feel calmer.

Is it safe?

In studies lasting up to three months, ashwagandha was well tolerated, with only mild side effects like upset stomach, loose stools, nausea, and drowsiness being reported. However, longer-term safety is unclear.

In 2023, Denmark banned ashwagandha, citing concerns about its potential to disrupt thyroid and sex hormones and to induce abortion.  

“It should be used cautiously in people with thyroid problems, and avoided during pregnancy and breastfeeding,” says Sarris. It may also be unsafe for people with prostate cancer.  

Ashwagandha can interact with certain medications, including thyroid drugs, diabetes and blood pressure medicines, sedatives, and immunosuppressants.

There have been very rare reports of liver issues from some ashwagandha supplements, says Sarris, but the identity or quality of the ashwagandha that triggered those cases is unknown.

What do experts recommend?

Because studies have used different forms of ashwagandha—with varying amounts of active compounds and different doses—it’s difficult to say which kind of supplements work best or exactly how much to take.

In 2022, an international task force set up by the World Federation of Societies of Biological Psychiatry and the Canadian Network for Mood and Anxiety Treatments recommended a daily dose of 300 to 600 milligrams of ashwagandha root extract containing five percent withanolides for the treatment of generalized anxiety disorder. But they emphasized that more research is needed before stronger recommendations can be made.

Given the gaps in data on optimal dosage, long-term safety, and effects across diverse populations, Curtis advises that “any continued use of the extract should be monitored carefully by a healthcare professional.”

Something else to keep in mind is supplement quality. “Supplements are not regulated as strictly as prescription medications so purity and potency can vary widely between brands,” says Sawhne. “Some products have even been found to contain contaminants or inconsistent doses.” She recommends choosing a brand that uses third-party testing, meaning an independent lab has verified that what’s on the label is what’s in the bottle and that it’s free of harmful contaminants.

Finally, it’s important to remember that ashwagandha isn’t a magic bullet, says Maniscalco. Basic healthy habits are important for keeping stress and sleep problems in check. This includes things like consistent bed and wake times, regular physical activity, a diet rich in whole foods, and stress-reducing practices like mindfulness or breathwork. And if stress or sleep problems are serious or getting worse, see a healthcare provider first, he says.

This story is part of Popular Science’s Ask Us Anything series, where we answer your most outlandish, mind-burning questions, from the ordinary to the off-the-wall. Have something you’ve always wanted to know? Ask us.

 

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