Ashwagandha
Also known as: Withania somnifera, Indian ginseng, Winter cherry
An adaptogenic herb from Ayurvedic medicine, best known for reducing stress and supporting sleep.
In short
Ashwagandha (Withania somnifera) is a small evergreen shrub whose root has been used in Ayurvedic medicine for centuries as a rasayana — a rejuvenating tonic. Modern trials, mostly 8–12 weeks in length, show standardized root extracts modestly reduce perceived stress and anxiety and may improve sleep. Its active compounds, withanolides, are thought to modulate the body's stress response, though the exact mechanism is still being studied.
- Adaptogenic herb from Ayurveda; root is the part used
- Active markers: withanolides
- Common studied doses: 300–600 mg of root extract daily
- Best evidence: stress, anxiety, and sleep quality
What is Ashwagandha?
Ashwagandha — Sanskrit for 'smell of the horse,' a nod to the root's aroma and its reputed strength-giving properties — is one of the most-studied herbs in Ayurveda and one of the fastest-growing supplements in the US market. It belongs to the adaptogen family, botanicals said to help the body resist physical and mental stress. The modern evidence base centers on standardized root extracts (often KSM-66 or Sensoril, standardized to withanolides) studied for stress, anxiety, sleep, and, to a lesser extent, physical performance.
Where it comes from
Natural sources
- Root of Withania somnifera, native to India, the Middle East, and parts of Africa
- Traditionally used as powder mixed with milk or honey
- Leaves are also used in some preparations
How it's made
Supplemental extracts are concentrated and standardized to withanolide content via water or ethanol extraction.
What it does in products
Benefits
Stress and anxiety reduction
moderate evidenceMultiple randomized trials report moderate reductions in perceived stress and anxiety scores with 300–600 mg daily over 8–12 weeks, supported by meta-analyses showing medium effect sizes.
Sleep quality
moderate evidenceTrials in people with insomnia symptoms found ashwagandha improved sleep onset and quality, with effects growing over 6–10 weeks; several studies measured lower cortisol.
Physical performance and strength
emerging evidenceSome small trials in resistance-trained adults report modest gains in strength and recovery with 300–600 mg twice daily, though the evidence is less consistent than for stress.
Testosterone and fertility support
emerging evidenceA few small studies in men report modest testosterone increases; findings are preliminary and inconsistent.
Side effects & safety
Safety considerations
- Ashwagandha is traditionally considered unsafe in pregnancy (potential to stimulate uterine activity) and should be avoided. Its safety in breastfeeding is not established.
- May amplify the effects of sedatives and sleep medications.
- Can affect thyroid hormone levels — monitor if you have thyroid disease or take thyroid medication.
- May modulate immune activity; caution with immunosuppressants.
- Not for: Pregnancy and breastfeeding
- Not for: Autoimmune conditions (rheumatoid arthritis, lupus, MS) — use only under supervision
- Not for: Planned surgery (stop two weeks prior, given its sedative and potential blood-sugar effects)
How it's used
In supplements
Standardized root extract: 300–600 mg daily for stress and sleep (studies often use 600 mg split into two doses). Full-spectrum extracts standardized to 2.5–5% withanolides are the most studied. Effects build over 4–8 weeks.
Regulatory status
- Dietary supplement under DSHEA; no FDA-approved medical use. Manufacturers are responsible for safety and accurate labeling.
Popular products containing Ashwagandha
- Ashwagandha 600 mg (KSM-66) — Standardized to 5% withanolidesNOW Foods · supplement
- Ashwagandha Root CapsulesGaia Herbs · supplement
- Organic AshwagandhaHimalaya · supplement
Product names and brands are shown for reference and belong to their respective owners.
What 'adaptogen' actually means
Adaptogens are herbs claimed to increase the body's nonspecific resistance to stress. The research framework centers on the HPA axis — the brain-adrenal loop that drives cortisol release. In some ashwagandha trials, morning cortisol levels dropped measurably, and stress questionnaires improved. That said, 'adaptogen' is a traditional and marketing category rather than a regulatory or strictly scientific one; individual products vary in standardization and evidence.
Frequently asked questions
How long does ashwagandha take to work?
It is not an acute anti-anxiety medication — benefits accrue over weeks. Most trials show meaningful changes at 6–12 weeks of daily use; some people notice better sleep within the first couple of weeks.
When is the best time to take ashwagandha?
If your goal is sleep, take it in the evening. For daytime stress, split the dose morning and evening. If it makes you drowsy, shift the entire dose to bedtime.
Who should not take ashwagandha?
Pregnant or breastfeeding women, people with autoimmune disease or thyroid disorders (unless supervised), those on sedatives, immunosuppressants, or thyroid medication, and anyone scheduled for surgery. As with any botanical, check with your doctor first.
The bottom line
Ashwagandha is one of the better-supported botanical options for everyday stress and sleep, with a reasonable safety record in 8–12 week trials. It is not for everyone — pregnancy, autoimmune, and thyroid conditions top the caution list — and benefits, like most adaptogens, appear gradually with consistent use.
References
- Ashwagandha. NCCIH (National Institutes of Health). https://www.nccih.nih.gov/health/ashwagandha
- An investigation into the stress-relieving and pharmacological actions of an ashwagandha extract. Medicine (Baltimore) — PMC. https://pmc.ncbi.nlm.nih.gov/articles/PMC6750292/
- Withania somnifera compound records. PubChem (National Library of Medicine). https://pubchem.ncbi.nlm.nih.gov/#query=Withania%20somnifera
- Ashwagandha for anxiety and stress — literature search. PubMed (National Library of Medicine). https://pubmed.ncbi.nlm.nih.gov/?term=ashwagandha+stress+randomized