Ashwagandha is an adaptogenic herb used in traditional Ayurvedic medicine, now widely sold for stress and sleep. Here is what the research actually supports — and what it does not.
What ashwagandha is
Ashwagandha (Withania somnifera) is classed as an “adaptogen,” a loose term for plants said to help the body cope with stress. Most supplements use a root extract, often standardized to a set percentage of compounds called withanolides.
What the research says
Several small randomized trials have reported reductions in self-reported stress and anxiety scores, and some measured lower cortisol. The studies are mostly small, short and industry-funded, so the evidence is best described as early and promising rather than settled. The U.S. National Center for Complementary and Integrative Health keeps a plain-language summary of ashwagandha that reflects this cautious reading.
Dosage and what to look for
Trials commonly use 250–600 mg per day of a standardized root extract. KSM-66 and Sensoril are two branded extracts used in much of the published research, which is why you often see them named on labels. Effects, if any, build over several weeks rather than in a single dose.
Ashwagandha Root Extract (look for KSM-66 or Sensoril)
- Standardized root extract, commonly 250–600 mg daily
- KSM-66 and Sensoril are the forms used in most published trials
- Give it several consistent weeks before judging
Widely available
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Short-term use appears well tolerated for most healthy adults, but there have been reports of liver injury in rare cases. It is not recommended during pregnancy, and it may interact with thyroid, sedative and immunosuppressant medications. If you take medication or have a health condition — particularly a thyroid or autoimmune condition — talk to your healthcare provider first.
Looking at sleep specifically? See our guide to the best sleep supplements.