Ashwagandha
One of the best-studied adaptogens — standardized extracts have been shown in clinical trials to lower perceived stress and cortisol levels.
Number of studies
2
Safety
Requires caution
Time to effects
The first subjective effects (calm, sleep) appear after 1–2 weeks; the full effect on perceived stress and cortisol seen in clinical trials takes 8–12 weeks of regular use.
Monthly cost
ok. 35–70 zł/miesiąc
Price in Poland
35–70 zł za 60 kapsułek ekstraktu KSM-66 (miesiąc stosowania)
Who it's for
Sensoril bywa nieco droższy niż KSM-66 przy porównywalnej dawce.
Indicative prices for the Polish market — we don't point to specific retailers; the real price depends on the manufacturer, form and place of purchase.
Table of contents
TL;DR
One of the best-studied adaptogens — standardized extracts have been shown in clinical trials to lower perceived stress and cortisol levels.
- →Possible reduction in subjectively perceived stress and anxiety
- →In some studies: lower morning cortisol in saliva/serum
- →Preliminary data suggest support for strength and post-exercise recovery
| Latin name | Withania somnifera |
|---|---|
| Group/class | Adaptogen (Ayurvedic rasayana) |
| Active compounds | Withanolides (incl. withaferin A, withanolide A) |
| Form | Extract standardized for withanolides (usually ≥5%), e.g. KSM-66, Sensoril |
| Evidence level | Moderate — well studied for an adaptogen, mostly 8–12-week trials |
| Interactions | Yes — sedative, thyroid and immunosuppressive medications |
| Status | Dietary supplement, available without a prescription |
Understand
Overview
Ashwagandha (Withania somnifera), also known as winter cherry or Indian ginseng, is a plant used for thousands of years in Ayurvedic medicine as a so-called rasayana — a remedy for supporting vitality and longevity. It grows mainly in India, the Middle East and North Africa, and its root is the part used medicinally.
Modern research focuses on standardized root extracts (e.g. KSM-66, Sensoril) with a defined and reproducible withanolide content, which sets them apart from traditional whole-root powders whose potency varies. Today ashwagandha is one of the most popular adaptogens on the supplement market, studied for its effects on stress, sleep, physical performance and cognitive function.
The people who benefit most from ashwagandha are those with chronic, measurable stress and elevated cortisol — this group dominated the clinical trials, which observed a significant reduction in perceived stress and cortisol levels compared with placebo. The effect builds gradually — meaningful changes typically appeared after 8–12 weeks of regular use, so this isn't a supplement for calming yourself down before a single stressful day. People without elevated baseline stress who are hoping for a testosterone boost 'for its own sake' in healthy, unstressed men should keep their expectations modest — the evidence in this narrower group is limited and less consistent than the evidence for stress and cortisol. Because of its contraindications (pregnancy, hyperthyroidism, autoimmune disease), some people shouldn't take ashwagandha at all without consulting a doctor first.
Where it's found
Withania somnifera grows wild in the dry and semi-arid regions of India, Pakistan and Sri Lanka, as well as the Middle East and North Africa, favoring poor, well-drained soil and a hot climate. It belongs to the nightshade family (Solanaceae) — the same family as tomatoes and potatoes. The part used in supplements and traditional medicine is the root, usually harvested in autumn from plants around one year old.
History of use
In Ayurveda, ashwagandha is classified as a rasayana — a group of herbs regarded as supporting vitality, stress resilience and longevity, used for thousands of years in traditional Indian medicine. The Sanskrit name 'ashwagandha' literally means 'smell of a horse' — traditionally explained both by the distinctive smell of the fresh root and by the belief that the plant confers the strength and vitality of a horse. It only became widely known in Western phytotherapy and the supplement industry in recent decades, alongside the development of standardized extracts (such as KSM-66 and Sensoril) that made it possible to dose withanolides consistently in clinical trials.
Mechanism of action
Withanolides — a group of steroidal lactones that are the main active compounds — modulate the hypothalamic-pituitary-adrenal (HPA) axis, which in studies is linked to lower cortisol levels in serum and saliva. Research also suggests an effect on GABAergic receptors (which would explain the relaxing effect), along with potential anti-inflammatory and antioxidant properties through a reduction in markers of oxidative stress.
Among the withanolides, most of the described effects are attributed mainly to withaferin A and withanolide A, which have been studied for their ability to inhibit the release of corticotropin-releasing hormone (CRH) in the hypothalamus, indirectly limiting the secretion of ACTH and cortisol from the adrenal cortex. Ashwagandha has also been studied for its effect on thyroid hormones (T3, T4) — hence the contraindication in hyperthyroidism — and on GABA-A receptor subunits, which may explain its reported calming and sleep-supporting effects, particularly with the Sensoril extract, which is richer in leaf-derived withanolides.
HPA axis modulation
Withanolides limit the release of corticotropin-releasing hormone (CRH) in the hypothalamus, which indirectly lowers ACTH and cortisol secretion from the adrenal glands.
Effect on GABA-A receptors
Withanolides interact with GABAergic receptors, which is linked to the reported calming and sleep-supporting effects.
Reduction of oxidative stress
The active compounds show antioxidant properties, lowering markers of oxidative stress associated with chronic stress.
Effect on the thyroid axis
Ashwagandha may increase thyroid hormone levels (T3, T4), which is why caution is warranted in hyperthyroidism.
Support for post-exercise recovery
Preliminary data suggest an effect on markers of inflammation and post-exercise recovery, though this mechanism is less well described than the effect on the HPA axis.
Evidence: moderate — based on 2 studies in this database.
Benefits
Common myths
MythAshwagandha works instantly, like a sedative.
FactIt's an adaptogen whose effect builds over time — most clinical trials observed significant effects only after 8–12 weeks of regular use, not after a single dose.
MythAshwagandha is safe for everyone because it's 'just an herb.'
FactIt's contraindicated in pregnancy, hyperthyroidism and autoimmune disease, among other conditions — being plant-derived doesn't mean it's free of contraindications.
Forms & variants
Ashwagandha comes in several forms that differ in bioavailability and use case — the form you pick genuinely matters for how effective the supplementation is.
KSM-66
The most widely studied extract on the market, produced by water extraction from the root alone (no leaves), standardized to at least 5% withanolides.
Best for: General stress support and physical performance — the broadest base of clinical research
Sensoril
An extract from both root and leaf, standardized to a higher withanolide content in a different ratio than KSM-66 — in studies more strongly associated with relaxing and sleep-supporting effects.
Best for: Evening sleep support and deep relaxation
Whole-root powder (traditional)
The form closest to traditional Ayurvedic use — variable, usually lower and non-standardized withanolide content, making it harder to compare doses between manufacturers.
Best for: People who prefer the traditional form and can accept less predictable dosing
Practice
Frequently asked questions
Most clinical trials lasted 8–12 weeks. Safety data for use beyond a few months is limited, so periodic breaks and a doctor's consultation are recommended for long-term use.
A few small studies in men with infertility or under stress showed an increase in testosterone, but the evidence in healthy men without these conditions is limited and needs confirmation in larger trials.
KSM-66 has a broader research base for general stress reduction and performance support, while Sensoril tends to be associated with stronger calming and sleep-supporting effects — the choice depends on your main goal for supplementing.
Most clinical trials observed significant effects after 4–8 weeks of regular use — it's not a substance with an immediate effect, unlike, say, L-theanine.
Dosage & timing
Typical dose
300–600 mg of standardized root extract per day
Form
Extract standardized for withanolide content (e.g. KSM-66 ≥5%)
Dosing is informational and reflects the ranges used in the cited studies — it does not replace consulting a doctor or pharmacist.
Best times to take it
- In the evening, if the goal is sleep
- Can be split into a morning and evening dose when the goal is stress reduction
What to combine with
Good combinations
Magnez — A common combination in anti-stress protocols
Use caution with
leki tarczycowe — Requires medical supervision in people with thyroid disease
Safety
Side effects & contraindications
Possible side effects
Possible drowsiness at higher doses
Rarely: gastrointestinal discomfort
Isolated case reports of liver injury — causal link unclear
Contraindications
Pregnancy and breastfeeding
Autoimmune diseases (potential immune stimulation) — consult a doctor
Hyperthyroidism — ashwagandha may increase thyroid hormone levels
Interactions
Sedatives/benzodiazepines — may intensify the sedative effect
Immunosuppressive drugs — theoretical interaction due to effects on the immune system
Levothyroxine and other thyroid medications
Is it worth taking?
Who it's for
- People with chronic stress and elevated cortisol levels
- People who have trouble falling asleep due to mental tension
- Athletes, in the context of post-exercise recovery
Not for
- Pregnancy and breastfeeding
- Autoimmune diseases (potential immune stimulation) — consult a doctor
- Hyperthyroidism — ashwagandha may increase thyroid hormone levels
Evidence
Worth knowing
KSM-66 and Sensoril are the two most widely studied extracts, but they're different — they vary in which part of the plant is used and the ratio of withanolides.
The name 'ashwagandha' means 'smell of a horse' in Sanskrit, referencing the traditional belief that it boosts vitality and strength.
The plant belongs to the same botanical family as tomatoes and potatoes (Solanaceae).
Studies
A meta-analysis of more than a dozen RCTs confirms it: standardized ashwagandha extract significantly lowers anxiety and cortisol levels compared with placebo.
Akhgarjand C. et al., Phytotherapy Research, 2022
A prospective, randomized double-blind, placebo-controlled study of Withania somnifera on stress and anxiety
Moderate evidenceChandrasekhar K, Kapoor J, Anishetty S. · Indian Journal of Psychological Medicine · 2012
A randomized, placebo-controlled trial (n=64) showing a significant reduction in perceived stress and cortisol levels in the group supplemented with ashwagandha root extract.
View studyAdaptogenic and Anxiolytic Effects of Ashwagandha Root Extract: A Systematic Review and Meta-analysis
Moderate evidenceAkhgarjand C, et al. · Phytotherapy Research · 2022
A meta-analysis of more than a dozen RCTs confirming a significant reduction in anxiety symptoms and cortisol levels compared with placebo.
View studySources & bibliography
Citations are illustrative for this demo version and require full bibliographic verification by the editorial team before production publication.
Compare with similar entries
About the authors of this entry
Author
Julia WiśniewskaEditor, Neurohacking & Sleep
Julia writes about nootropics, chronobiology and recovery protocols.
34 publications on this site
Medical review
dr Anna KowalczykEditor-in-Chief, Molecular Biology
Anna oversees the editorial process and scientific review of every publication in the knowledge base. She previously researched autophagy and mitochondrial biology.
26 publications on this site
Related entries
4.2Rhodiola Rosea (Golden Root)
An adaptogen traditionally used for mental and physical fatigue — research is promising, but less extensive than for ashwagandha.
4.5Cortisol
The main stress hormone — essential for short-term survival, but problematic when chronically elevated.
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Comments (2)
- KW
Kasia W. 2 weeks ago
Very clearly explained, especially the interactions section — I hadn't seen it laid out this well anywhere else.
- MT
Marek T. a month ago
Are you planning to update this with the newest study from this year? I saw an interesting meta-analysis.