Ashwagandha may help some adults with short-term stress or sleep concerns, but benefits are inconsistent, anxiety evidence is unclear, and long-term safety remains uncertain.
Mixed evidence
Human studies suggest possible short-term benefits for selected stress and sleep outcomes, while findings for perceived stress and anxiety remain inconsistent and product formulations vary widely.
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Overview
Ashwagandha may improve sleep quality or some stress measures for certain adults over the short term.
A lower cortisol reading does not necessarily mean a person feels less stressed.
Evidence for anxiety relief is still unclear, especially outside specific clinical populations.
Root, leaf, and root-and-leaf products are not interchangeable, so a study of one extract does not prove that every supplement works.
Short-term use appears better studied than long-term use, and rare liver injury and medication interactions matter.
One idea at a time
Human evidence for ashwagandha suggests possible short-term sleep and stress benefits, with important outcome, formulation, and safety limits.
The short answer is a qualified maybe.
Oral ashwagandha may improve sleep quality and some measures of stress for certain adults over roughly one to three months. The signal is stronger for selected sleep or stress outcomes than for anxiety, and results do not automatically apply to every root, leaf, or root-and-leaf product.
The main limitation is that the studies are small and use different extracts, doses, treatment periods, and outcome measures. A supplement can lower a laboratory marker without producing a noticeable improvement in daily well-being, so the type of outcome matters.[8][5][6]
Ashwagandha, or Withania somnifera, contains compounds called withanolides. Cortisol is a hormone involved in the body’s response to stress, so researchers often measure it as a biological marker. The proposed biology is plausible, but the exact mechanisms and the importance of changing cortisol in otherwise healthy adults are not settled.
A 2025 meta-analysis of randomized trials found a reduction in cortisol across seven studies, but no statistically clear improvement in perceived stress across six studies involving 488 participants. The studies had moderate variation and generally moderate risk of bias. This is a useful warning against treating cortisol as a stand-in for how someone feels.[8][5][6]
Stress results depend on the extract and the study.
One newer randomized, double-blind trial followed 90 adults with non-chronic mild-to-moderate stress for 84 days. A branded formulation called Zenroot improved perceived stress, anxiety questionnaire scores, and sleep scores compared with placebo at several time points. However, it did not significantly change serum cortisol. The product was well tolerated in this study, but the trial tested that specific formulation rather than ashwagandha as a whole.
A smaller randomized trial in 60 healthy college students used a full-spectrum root extract for 30 days. An adjusted follow-up analysis found better final sleep scores in the ashwagandha group, but the primary group-by-time analysis for sleep and stress was not significant, and baseline sleep influenced the stress result. A companion qualitative analysis reported participant experiences involving sleep, energy, and mental clarity, but those reports are not the same as a blinded clinical outcome.[7][4]
Sleep has a clearer signal than anxiety, but neither is proven for everyone.
In a placebo-controlled trial, 150 healthy adults with prominent non-restorative sleep symptoms took a standardized extract or placebo for six weeks. Of the 144 people who completed the study, the extract group reported a larger improvement in overall sleep quality than the placebo group. Researchers also measured sleep-onset latency, sleep efficiency, total sleep time, and nighttime waking with actigraphy, but the available report does not establish that ashwagandha improves each of those specific measures.
The National Center for Complementary and Integrative Health concludes that some preparations may help insomnia and stress, while evidence for anxiety remains unclear. One 12-week study found improvements in anxiety-related scores among 66 people with schizophrenia receiving standardized ashwagandha alongside their usual care. That result is promising but comes from a specific clinical population and a secondary analysis, so it does not establish an anxiety treatment effect for generally healthy adults.[2][8]
Safety and product quality set important boundaries.
NCCIH says ashwagandha may be safe for short-term use of up to about three months, but there is not enough information to judge long-term safety. Reported side effects include drowsiness, stomach upset, diarrhea, and vomiting. Rare cases have linked ashwagandha supplements with liver injury, and the human cortisol literature has not adequately examined long-term effects or whether lowering cortisol could affect adrenal function.
Ashwagandha should be avoided during pregnancy and breastfeeding and is not recommended before surgery or for people with autoimmune or thyroid disorders, according to NCCIH. It may interact with medicines for diabetes or high blood pressure, sedatives, anti-seizure medicines, immunosuppressants, and thyroid hormone. Because dietary supplements are not approved by the FDA before sale, the label, extract type, and quality controls matter; a positive trial of one standardized product is not proof for an unlabeled or differently formulated product.[8][5]
Sources (2 sources)
Research & sources
8 original papers and authoritative references used for this explainer.
