Sleep and stressModerate evidence
Ashwagandha
Also called: Withania somnifera, Indian ginseng, winter cherry, root extract standardized to withanolides.
An Ayurvedic root sold for stress and sleep, whose trials rest on specific standardized extracts, with liver and thyroid signals you should know about.
What it is
Ashwagandha (Withania somnifera) is a shrub whose root is used as an adaptogen (a plant said to help the body adapt to stress) in Ayurvedic medicine. Its studied compounds are withanolides, steroidal lactones. It is sold mostly for stress, sleep and, in men, testosterone.
What the label does not say
- The number to read is the withanolide content and the plant part, not just the milligrams: 5% root extract, root and leaf extract standardized to glycosides and raw powder all go by the name ashwagandha, and the Canadian monograph requires no standardization.
- The trial dose is 300 to 600 mg of standardized extract per day for 6 to 12 weeks, with stronger effects on stress at 500 to 600 mg and, on sleep, at 600 mg and at 8 weeks or more. A format that puts a fraction of that per unit, jujube or gummy, is judged on the daily total and on the withanolide content.
- Cortisol drops more reliably than felt stress. A 2025 meta-analysis (7 trials, 488 people) reports a cortisol drop of 1.16 µg/dL with no significant effect on perceived stress; another (15 trials, 873 people) reports drops in stress and anxiety scores at 8 weeks, with no gain in quality of life. The trials are small, short and mostly Indian.
- The liver. LiverTox (NIH) lists about 23 cases of clinically apparent liver injury, 2 to 12 weeks after starting, mostly cholestatic with jaundice and itching, resolved within 1 to 4 months after stopping, with rare fatal cases or transplants in people who already had liver disease. In July 2026, Health Canada did not find sufficient evidence of a definite link, without being able to rule it out, and the 2025 Canadian monograph does not mention the liver: so the label says nothing about it.
The forms on the shelf
- Root-only extract standardized to at least 5% withanolides, in 300 mg capsules: the extract used in most of the stress and sleep trials, at 300 to 600 mg per day.
- Root and leaf extracts, standardized differently (for example 21 mg of withanolide glycosides per 60 mg capsule, at 120 mg per day): the chemical composition of the leaf differs from that of the root according to the NIH, and the milligrams cannot be compared from one extract to another.
- Non-standardized root powder: the Health Canada monograph covers it at 2 to 6 g of dried root per day, with no standardization required. Six hundred milligrams of powder is not 600 mg of extract.
Published reference values
- No recommended intake. Trials: 300 to 600 mg of standardized extract per day, 6 to 12 weeks. Health Canada: 2 to 6 g of dried root per day, 2.5 to 6.5 g for the adaptogen claim.
- The NIH describes it as well tolerated for up to about 3 months; safety beyond that is not known. Common effects: stomach upset, loose stools, nausea, drowsiness.
- Thyroid: small rises in T4 in 3 men at 500 mg per day, and 3 cases of thyrotoxicosis in women, including one at 1,950 mg per day for more than 2 months, resolved on stopping.
- Pregnancy: reports raise a risk of miscarriage; Denmark banned it in 2023 and France's ANSES advises against it during pregnancy and breastfeeding, where Health Canada asks you to consult.
When
Every day, often in two doses, for at least 6 to 8 weeks in the trials; the effect is not that of a bedtime dose. The Canadian monograph warns of possible drowsiness while driving.
Keep apart from
- Sedatives and hypnotics: additive drowsiness (NCCIH).
- Antidiabetics and antihypertensives: possible interactions reported by the NIH.
- Immunosuppressants, anticonvulsants and thyroid hormones: interactions reported by the NCCIH; ashwagandha can raise T4.
To mention to a professional
- Liver disease or cirrhosis, thyroid disorder, autoimmune disease, hormone-sensitive prostate cancer, planned surgery, pregnancy and breastfeeding, and any sign of liver injury during use (jaundice, itching, nausea, unusual fatigue): check with a health care professional.
Sources
- NIH Office of Dietary Supplements, Ashwagandha: Is it helpful for stress, anxiety, or sleep? (Health Professional)
- NCCIH, Ashwagandha
- NIH LiverTox, Ashwagandha
- Health Canada, natural health product monograph, Ashwagandha (Withania somnifera), 2025
- Health Canada, Health Product InfoWatch, August 2026 (safety review, ashwagandha and hepatotoxicity)
- Cheah et al., Effect of Ashwagandha (Withania somnifera) extract on sleep: A systematic review and meta-analysis, PLoS One, 2021
- Albalawi, Dual impact of Ashwagandha: Significant cortisol reduction but no effects on perceived stress, Nutrition and Health, 2025
- Effects of Ashwagandha Supplements on Cortisol, Stress, and Anxiety Levels in Adults: A Systematic Review and Meta-Analysis, BJPsych Open, 2025
Educational information, drawn from the sources above. It does not replace the advice of a health professional, who remains the reference for your situation, your medications, pregnancy or breastfeeding.