Ashwagandha for Stress and Sleep: What Studies Can Tell Us

Research on ashwagandha for stress and sleep is promising but limited. Several small trials, most of them run in India and lasting 6 to 12 weeks, found that ashwagandha extracts lowered scores on stress rating scales and improved some sleep measures compared with placebo. The products tested were mostly standardized extracts, in doses and forms that vary from study to study, so the results do not transfer neatly to any one supplement. Safety data cover only about 3 months of use.

What the studies actually measured

Ashwagandha (Withania somnifera) is a shrub whose root has long been used in Ayurvedic medicine. Most of the human research tests it for three things: how stressed people say they feel, a stress hormone called cortisol, and sleep. These are different outcomes, and the evidence for each is not equally strong.

Outcome	How it was measured	What the sources report
Perceived stress	Validated rating scales filled in by participants	Lower scores than placebo in most trials summarized by NIH ODS
Cortisol	Blood or saliva levels	Lower in several trials; a hormone level is a marker, not a measure of how you feel
Sleep	Sleep questionnaires and wrist activity monitors (actigraphy)	A small but significant overall effect in a 2021 meta-analysis
Anxiety scores	Clinician or self-rated anxiety scales	NCCIH says the evidence about anxiety is unclear

Ashwagandha and stress: what the trials found

The NIH Office of Dietary Supplements (ODS) summarizes a 2021 systematic review of seven trials in 491 adults, all from India, who had self-reported high stress and anxiety or a diagnosed anxiety disorder. Participants took ashwagandha or placebo for 6 to 8 weeks. Overall, the studies found lower stress and anxiety ratings, less sleeplessness and fatigue, and lower serum cortisol than with placebo, and in several studies the benefits appeared greater at 500 to 600 mg a day than at lower doses.

The preparations differed. Six of the seven studies used extracts, made from the root alone, from root and leaf, or from unspecified parts, at 240 to 1,250 mg of extract a day. The seventh used whole-root granules at 12,000 mg a day, which ODS says is equivalent to 6,000 mg of root powder. Later trials described by ODS mostly point the same way, though one 12-week trial of a root extract found less fatigue but no drop in perceived stress compared with placebo.

A 2021 review by Speers and colleagues in Current Neuropharmacology reached a similar view: benefits were seen, but the variety of extracts tested prevents a consensus on the best preparation or dose.

Ashwagandha and sleep: what the trials found

A 2021 meta-analysis by Cheah and colleagues in PLoS One pooled five randomized controlled trials with 400 adults. Ashwagandha extract had a small but significant effect on overall sleep compared with placebo. The effect was more prominent in adults diagnosed with insomnia, at doses of 600 mg a day or more, and when treatment lasted 8 weeks or longer. The authors note that data on serious adverse effects are limited and that more safety data are needed before judging long-term use.

One of those trials, published in 2021 by Langade and colleagues in the Journal of Ethnopharmacology, enrolled 80 adults in India: 40 healthy and 40 with insomnia. According to ODS, participants took two 300 mg capsules a day of a root extract standardized to more than 5% withanolides, or placebo, for 8 weeks. Sleep measures improved in both groups taking ashwagandha, with larger changes in the insomnia group; anxiety scores and mental alertness on rising improved only in the insomnia group. The authors call for more trials before the results can be generalized.

Why study doses do not translate to a label

ODS notes that because studies used different preparations, with different extraction and standardization processes, and different doses, it is difficult to identify specific extracts or recommended amounts. When you compare a label with the research, check three things:

• Plant part: root, leaf, or root and leaf. ODS says the chemical makeup of root and leaf differs.
• Form: a concentrated extract, often standardized to a percentage of withanolides, or the root itself.
• Amount per day: the milligrams per serving times the servings the directions call for.

An extract and the root are different forms, so their milligram figures are not the same thing, and a trial of one form does not show what another form will do. Neither is described by ODS as the correct one.

How the Ashwagandha+ label compares

Ashwagandha+ lists 650 mg of ashwagandha root and 5 mg of black pepper fruit per 1-capsule serving. The suggested use is one capsule daily, preferably 20-30 minutes before a meal, or as directed by your healthcare professional. It is ashwagandha root, and the label does not state a withanolide percentage, so the extract trials above were not testing this form or this amount, and their results cannot be assumed to apply to it. The one study in the 2021 review that used the root itself gave 12,000 mg of root granules a day, which ODS says equals 6,000 mg of root powder; that is far more than the 650 mg in one Ashwagandha+ capsule. The label warning reads: "Do not exceed the recommended dose. Pregnant or nursing mothers, children under 18, and individuals with a known medical condition should consult a physician before use. Keep out of reach of children. Do not use if the safety seal is damaged or missing. Store in a cool, dry place."

If another formula you take also lists ashwagandha, add the amounts together and do not double up.

Safety: what to know before you try it

NCCIH says ashwagandha may be safe when taken in the short term, up to 3 months, and that there is not enough information to reach conclusions about its long-term safety. In some people it may cause drowsiness, stomach upset, diarrhea and vomiting.

Although it is rare, NCCIH says a number of cases have linked liver injury to ashwagandha supplements. ODS describes reported signs such as jaundice (yellowing of the skin or eyes), itching, nausea, lethargy and abdominal discomfort. If you notice signs like these, stop using the supplement and contact your health care provider.

NCCIH also says ashwagandha should be avoided during pregnancy and should not be used while breastfeeding. If you are pregnant, nursing or trying to conceive, ask your healthcare provider before use. NCCIH says it is not recommended for people about to have surgery or for those with autoimmune or thyroid disorders, and people with hormone-sensitive prostate cancer should avoid it.

Ashwagandha might interact with medicines for diabetes and high blood pressure, immunosuppressants, sedatives, anti-seizure medicines and thyroid hormone medicines, according to NCCIH. If you take any medicine, talk with your health care provider first.

Frequently asked questions about ashwagandha for stress and sleep

Does ashwagandha help with sleep?

Some trials suggest a small benefit. The 2021 Cheah meta-analysis found a small but significant effect of ashwagandha extract on overall sleep, more prominent in adults with insomnia, at 600 mg a day or more, and over 8 weeks or longer.

Is it better to take ashwagandha in the morning or at night?

The sources reviewed here do not compare morning and night use. Trials gave a daily dose, sometimes split into two capsules. Drowsiness is a possible side effect, so notice how ashwagandha affects you before driving. Follow the directions on your product's label.

How long does ashwagandha take to work?

No source gives a timeline for an individual. The stress trials in the 2021 review lasted 6 to 8 weeks, and in the sleep meta-analysis the effect was more prominent with treatment lasting 8 weeks or longer. Individual results vary.

Are ashwagandha extracts and ashwagandha root the same?

No. An extract concentrates compounds from the plant and is often standardized to a percentage of withanolides, while root is the plant part itself. Because the forms differ, their milligram amounts cannot be compared one to one.

Can you take ashwagandha long term?

Long-term safety is not known. ODS says ashwagandha appears well tolerated for up to about 3 months, and that the efficacy and safety of use over months or years for stress, anxiety or sleep is not known.

Related reading

• Ashwagandha+
• Optional next step: our supplement audit can help you organize your goals; it does not diagnose anything.

Sources

• NIH Office of Dietary Supplements: Ashwagandha: Is it helpful for stress, anxiety, or sleep? (Fact Sheet for Health Professionals), updated May 2, 2025.
• National Center for Complementary and Integrative Health: Ashwagandha: Usefulness and Safety, last updated March 2023.
• Cheah KL, et al. Effect of Ashwagandha (Withania somnifera) extract on sleep: A systematic review and meta-analysis. PLoS One (PubMed 34559859), 2021.
• Langade D, et al. Clinical evaluation of the pharmacological impact of ashwagandha root extract on sleep in healthy volunteers and insomnia patients: A double-blind, randomized, parallel-group, placebo-controlled study. Journal of Ethnopharmacology (PubMed 32818573), 2021.
• Speers AB, et al. Effects of Withania somnifera (Ashwagandha) on Stress and the Stress-Related Neuropsychiatric Disorders Anxiety, Depression, and Insomnia. Current Neuropharmacology (PubMed 34254920), 2021.

The Dose Analysis and CuraMyHealth are both operated by Hofer LLC. Purchases linked from our reviews take place on CuraMyHealth.

This article is for education and is not personal medical advice. A qualified healthcare professional can help assess your needs and review the specific formula. Individual results vary.

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.