Walk into any supplement aisle and you’ll spot it: ashwagandha. The dusty-yellow root, native to India, North Africa, and parts of the Middle East, has spent the last decade quietly climbing into the global wellness mainstream. Sales of ashwagandha products in the United States crossed the $90 million mark in 2024, according to the American Botanical Council’s annual herb market report, a figure that has roughly doubled in five years.
Behind the marketing buzz sits a 3,000-year-old Ayurvedic tradition and, more recently, a growing stack of clinical trials. Research suggests ashwagandha may modestly lower perceived stress and the stress hormone cortisol, improve sleep quality, and help some adults feel calmer under pressure. But the herb is not a sedative, an anxiolytic drug, or a cure-all, and the evidence has real limits worth understanding before reaching for a bottle.
What Is Ashwagandha, Exactly?
Ashwagandha (Withania somnifera) is a small evergreen shrub in the nightshade family. In Sanskrit, its name roughly translates to “smell of the horse,” a nod both to the earthy aroma of its root and to the ancient belief that it conferred equine strength and stamina.
In Ayurvedic medicine, ashwagandha is classified as a rasayana, a rejuvenating tonic, and as an adaptogen, a category of herbs traditionally used to help the body resist physical, chemical, and biological stress. The plant’s active compounds include a family of steroidal lactones called withanolides, with withaferin A among the most extensively studied. Standardized commercial extracts, such as KSM-66 and Sensoril, are typically calibrated to deliver a specific percentage of withanolides per dose.
What the Research Says About Stress and Cortisol
Cortisol, the hormone released by the adrenal glands during stress, has become a household word in the wellness world. Chronically elevated cortisol has been linked in observational studies to disrupted sleep, weight gain around the abdomen, blood sugar dysregulation, and impaired immune function, according to background published by the National Institutes of Health.
Several randomized controlled trials have measured ashwagandha’s effect on stress markers in adults. A 2019 study published in Medicine randomized 60 adults with chronic stress to either 240 mg of standardized ashwagandha extract daily or a placebo for 60 days. Participants taking ashwagandha reported significantly lower scores on the Hamilton Anxiety Rating Scale and showed reduced morning cortisol compared with placebo.
A 2021 systematic review in the Journal of Ethnopharmacology pooled data from seven trials covering nearly 500 adults. The authors concluded that ashwagandha was associated with statistically significant reductions in self-reported stress and anxiety, though they cautioned that most studies were small, short (typically 8 to 12 weeks), and varied in extract type and dose.
A separate meta-analysis published in 2022 in Cureus examined cortisol specifically. Across five trials, ashwagandha supplementation was associated with a modest but consistent reduction in morning serum cortisol relative to placebo. The effect sizes were meaningful but not dramatic, and researchers emphasized that results in healthy adults under everyday stress may differ from those in people with diagnosed anxiety disorders.
Sleep, Energy, and the Broader Adaptogen Promise
The species name somnifera literally means “sleep-inducing,” and modern trials echo the traditional reputation. A 2020 randomized controlled trial in Cureus tested 600 mg of ashwagandha extract daily in 80 healthy adults and 80 adults with insomnia. After eight weeks, both groups reported improvements in sleep onset latency, total sleep time, and sleep quality scores, with the largest gains in the insomnia subgroup.
A 2021 meta-analysis in PLOS One covering five trials concluded that ashwagandha produced small-to-moderate improvements in sleep quality, particularly at doses of 600 mg or more per day and when taken for at least eight weeks. Subjective ratings of daytime alertness and mental fatigue also improved in several trials, although objective measures such as polysomnography were rarely used.
Research on ashwagandha for athletic performance, testosterone, and cognition is more preliminary. Some small trials suggest possible benefits for muscle recovery, VO2 max, and memory, but the studies are short and often industry-funded, and independent replication is limited. Studies indicate that the strongest evidence to date sits in the stress, anxiety, and sleep domains.
Dosing, Forms, and Quality
Most clinical trials have used standardized root extracts, typically 300 to 600 mg per day, often split into two doses with meals. Extracts labeled with a standardized withanolide percentage (usually 1.5% to 5%) tend to be better characterized in research than generic powdered root.
The U.S. Food and Drug Administration regulates ashwagandha as a dietary supplement, which means products are not reviewed for safety or efficacy before reaching shelves. Independent testing organizations such as USP, NSF, and ConsumerLab have repeatedly flagged supplements that fail to match label claims or that contain heavy-metal contaminants, so third-party certification on the bottle is one practical signal of quality.
Who Should Be Cautious
Ashwagandha is generally well tolerated in clinical trials, with mild gastrointestinal upset and drowsiness being the most commonly reported side effects. However, several groups should be especially cautious or avoid the herb entirely:
- Pregnant and breastfeeding people. Ashwagandha has traditionally been considered abortifacient in high doses, and safety data in pregnancy is lacking.
- People with autoimmune disease. Ashwagandha may stimulate immune activity, which could theoretically worsen conditions such as lupus, rheumatoid arthritis, or multiple sclerosis.
- People with thyroid conditions. The herb may increase thyroid hormone levels, which can be problematic for those with hyperthyroidism or those taking levothyroxine.
- People on sedatives, immunosuppressants, or blood pressure or diabetes medications. Ashwagandha may amplify or interact with these drug classes.
- People with liver disease. Rare case reports of liver injury linked to ashwagandha have appeared in the LiverTox database maintained by the National Institutes of Health, prompting calls for caution and monitoring.
Putting It in Perspective
Ashwagandha is one of the better-studied herbs in the modern adaptogen category, and the existing evidence supports a modest role in managing everyday stress and improving sleep quality for many adults. It is not, however, a replacement for therapy, medication, or the foundational habits, including adequate sleep, regular movement, balanced nutrition, and social connection, that drive long-term stress resilience.
If you are considering ashwagandha for chronic stress, anxiety, or sleep issues, consult your healthcare provider, especially if you take prescription medications or have an underlying medical condition. A clinician can help weigh the evidence against your personal health profile and identify whether the underlying stress signal deserves attention beyond a supplement bottle.
Disclosure: This content is for informational purposes only and is not medical advice. Always consult a qualified healthcare provider before making changes to your health regimen.