Ashwagandha: what the evidence says about stress and sleep

Ashwagandha is an evergreen shrub from India, Africa and the Middle East, used for thousands of years in Ayurvedic medicine. Supplements are made from the root, the leaf or both, and are mostly sold for stress, anxiety, sleep, male fertility and athletic performance NCCIH. Its active compounds are thought to include a group called withanolides.

Unlike most pages on this site, ashwagandha is not a kitchen food. The trials below used extracts in capsules, so everything here is about supplement doses.

A 2022 meta-analysis pooled 12 randomized trials with 1,002 participants. Ashwagandha lowered stress and anxiety scores compared with placebo, and the dose-response analysis suggested the stress benefit sat at 300 to 600 mg a day. The authors rated the certainty of evidence low for both outcomes and called for better trials Akhgarjand 2022.

Not every pooled analysis agrees. A 2025 meta-analysis found a significant drop in cortisol, a stress hormone, but no significant effect on the Perceived Stress Scale across six trials Albalawi 2025. A change in a hormone level is not the same as feeling less stressed.

The trials also tested a variety of preparations, so a result for one extract does not carry over to every product on the shelf. NCCIH sums it up as: some ashwagandha preparations may help with stress and insomnia, the evidence on anxiety is unclear, and many of the studies were small NCCIH.

If stress is wearing you down, the basics with stronger evidence still come first: sleep, movement, and talking to a clinician if worry or low mood is getting in the way of daily life. See our stress page for those.

A 2021 systematic review and meta-analysis found five placebo-controlled trials with 400 adults. Ashwagandha extract had a small but significant effect on overall sleep. The effect was clearer in adults diagnosed with insomnia, at doses of 600 mg a day or more, and when taken for at least 8 weeks. It also improved mental alertness on waking. No serious side effects were reported, but the authors noted that safety data were too thin to judge long-term use Cheah 2021.

For insomnia that lasts, our sleep page covers the approach guideline bodies put first, cognitive behavioral therapy for insomnia (CBT-I), before any supplement.

Ashwagandha seems safe for most people in the short term (up to 3 months), but there is not enough information on long-term use. It can cause drowsiness, stomach upset, diarrhea and vomiting, and although it is rare, a number of cases have linked liver injury to ashwagandha supplements NCCIH.

A case series from Iceland and the US Drug-Induced Liver Injury Network described five people who developed jaundice after 2 to 12 weeks on ashwagandha products. Itching and high bilirubin lasted 5 to 20 weeks; none developed liver failure, and liver tests returned to normal within 1 to 5 months in the four patients who were followed up Bjornsson 2020.

NCCIH also says ashwagandha is not recommended for people with thyroid disorders or autoimmune disease, and that it may interact with thyroid hormone medicine, diabetes and blood pressure drugs, immunosuppressants, sedatives and anti-seizure medicines. Because it may raise testosterone, people with hormone-sensitive prostate cancer should avoid it NCCIH.

Agree it with your clinician first if you take any regular medicine. The trials above mostly used root or root-and-leaf extracts at 300 to 600 mg a day Akhgarjand 2022; Cheah 2021, and NCCIH notes that supplements are not approved by FDA before sale, so contents vary between brandsNCCIH. Plain dried root powder is also sold; online, iHerb lists ashwagandha root powders and extracts if you want to compare what each label contains.

If you are choosing between this and tulsi, see ashwagandha vs holy basil.