Ashwagandha and Cortisol: The Science Behind Stress Relief

Last reviewed: May 21, 2026 · Reviewed by the YourHealthier Science Team · Editorial Policy

Cortisol is not the villain it's made out to be. It pulls you out of bed in the morning, helps regulate blood sugar between meals, modulates inflammation when you need it suppressed, and mobilizes glucose during acute stress. Andrew Huberman of Stanford School of Medicine opened his August 2025 cortisol episode^[12] by saying cortisol is at root an energy-direction hormone, not a stress hormone — and that one of his bigger wishes is for people to stop treating it as the enemy.

The problem is the rhythm, not the molecule. In a healthy adult, cortisol peaks within an hour of waking, declines through the afternoon, and reaches a low point around midnight. Chronic stress flattens this curve. Cortisol stays elevated through the evening, sleep onset gets harder, morning cortisol becomes blunted, and the whole HPA-axis feedback loop loses its sensitivity. That's the state ashwagandha addresses, not stress itself, but a dysregulated cortisol rhythm.

Ashwagandha (Withania somnifera) is the most clinically tested adaptogen for this specific problem. The 2025 meta-analysis by Bachour and colleagues at Tishreen University pooled 15 randomized controlled trials covering 873 adults and concluded that supplementation reduced cortisol and anxiety compared with placebo at 8 weeks.^[1] A second 2025 review by Albalawi and colleagues at the University of Tabuk added an honest complication: cortisol fell by an average of 1.16 µg/dL across seven trials (P < 0.001), but perceived stress on the PSS scale did not differ significantly from placebo across six trials (P = 0.40).^[2] We'll come back to that disconnect, it's the most useful nuance in the entire field.

We make and sell an Ashwagandha Plus supplement. We'll cover the formulation transparently and tell you where the evidence is strong, where it's mixed, and where we think honest practitioners disagree.

How ashwagandha affects the cortisol pathway

The hypothalamic-pituitary-adrenal axis is a three-step hormonal cascade. The hypothalamus releases corticotropin-releasing hormone (CRH). CRH tells the pituitary to release adrenocorticotropic hormone (ACTH). ACTH tells the adrenal glands to produce cortisol. In a healthy system, rising cortisol feeds back to the hypothalamus and pituitary to shut the cycle down. The loop self-regulates.

Chronic stress breaks the feedback. The system stays activated even when no acute threat is present. According to Adrian L. Lopresti, PhD, of Murdoch University in Perth, Australia — who led the 2019 Shoden ashwagandha trial, the active compounds in Withania somnifera, primarily withanolides and sitoindosides, appear to restore the sensitivity of that negative feedback loop and modulate GABAergic signaling in the brain at the same time.^[3] The net effect: cortisol output comes down, and the diurnal rhythm, high morning, low night — starts to look more like a healthy curve.

Bioactive content matters here. Standardized root extracts (the kind used in clinical trials) contain steroidal lactones, glycowithanolides, sitoindosides, and over 40 distinct withanolides at consistent concentrations. The 2026 Coope study published in Nutrients notes that across trials using standardized extracts at 125–600 mg/day for 4–12 weeks, cortisol reductions appeared consistently in healthy adults and in adults with mild-to-moderate stress.^[4]

Generic ashwagandha powder is a different molecule profile. Withanolide content can range from under 1% to over 5% depending on plant part, harvest, and extraction method. That's the reason clinical trials almost exclusively use standardized branded extracts.

What the clinical evidence shows

Bachour et al., 2025, the largest meta-analysis

Published in BJPsych Open in June 2025. George Bachour and colleagues at Tishreen University in Latakia, Syria, searched PubMed, Web of Science, Scopus, and the Cochrane databases through September 2024 and identified 15 randomized clinical trials investigating ashwagandha versus placebo in adults with stress or anxiety. Combined sample: 873 patients. The pooled effect on anxiety (HAM-A) was significant (P = 0.0007), and the pooled effect on cortisol was significant at 8 weeks (P < 0.0001).^[1] This is the broadest synthesis to date and the reason most newer reviews use 8 weeks as the minimum trial duration.

Albalawi et al., 2025, the dual-impact paper

Published August 2025 in Nutrition & Health. A PRISMA-compliant systematic review of seven RCTs measuring cortisol and six measuring the Perceived Stress Scale (n = 488 participants total). The result splits cleanly: serum cortisol dropped by 1.16 µg/dL on average (95% CI: −1.64 to −0.69, P < 0.001), but perceived stress did not differ significantly from placebo (SMD = −0.355, P = 0.40).^[2] The authors flagged moderate heterogeneity (I² = 50.9%) and noted that the cortisol effect appears to outpace the subjective experience of relief. This is the most important caveat in the literature. Biological measurements move. Self-reported feelings of stress sometimes don't follow.

Chandrasekhar, Kapoor, Anishetty, 2012 — the landmark KSM-66 trial

Published in Indian Journal of Psychological Medicine. Sixty-four adults with chronic stress randomized to KSM-66 ashwagandha root extract 300 mg twice daily (600 mg total) versus placebo for 60 days. The ashwagandha group showed a 27.9% reduction in serum cortisol versus 7.9% in placebo. Improvements across the Perceived Stress Scale, the General Health Questionnaire-28, and the Depression Anxiety Stress Scales were significant.^[5] This trial established 600 mg/day of KSM-66 as the benchmark dose for cortisol reduction, and is the reason most KSM-66 products use that exact dose.

Lopresti et al., 2019, the Shoden 240 mg trial

Published in Medicine. Sixty stressed but otherwise healthy adults took 240 mg of standardized Shoden ashwagandha extract (35% withanolide glycosides) or placebo for 60 days. Morning cortisol dropped in the treatment group (P < 0.001), DHEA-S also dropped (P = 0.004), and HAM-A anxiety scores improved (P = 0.040).^[3] This trial matters because it demonstrated cortisol effects at a much lower dose — Shoden's high withanolide concentration delivers a comparable dose of active compound from a smaller capsule.

Coope et al., 2026, sex-specific HPA response in athletes

Published January 2026 in Nutrients. A randomized, double-blind, placebo-controlled trial enrolled 56 team-sport athletes from a professional sports academy in Barcelona (rugby, water polo, football; 28 male, 28 female) on 600 mg/day of KSM-66 ashwagandha or placebo for 42 days of pre-season training. Salivary cortisol stabilized in the supplemented group during a training period that elevated cortisol in placebo. Female athletes showed stronger HPA-axis activation under training stress than males, a known sex difference that has been understudied — and the ashwagandha response differed by sex.^[4] The same lab published an earlier 2025 paper in the European Journal of Sport Science using a 4-week protocol in 30 female footballers, where the strength improvements were less consistent, suggesting longer durations matter more for female athletes specifically.^[6]

AshwaSR trial, March 2026, sustained-release formulation

Published March 13, 2026 in Medicine. A three-arm randomized, double-blind, placebo-controlled trial of 135 adults (PSS scores 14–26 at baseline) compared sustained-release ashwagandha root extract at 150 mg, 300 mg, and placebo for 60 days. PSS scores dropped 38.6% from baseline in the 150 mg group and 41.6% in the 300 mg group (P < 0.0001 within-group; both significantly better than placebo at P < 0.05). Serum cortisol fell only in the 300 mg group (P < 0.05).^[7] The dose-response signal here is important: subjective stress responded to lower doses, but the cortisol biomarker only moved at the higher dose. That's consistent with the Albalawi finding — these are partially separable outcomes.

Langade et al., 2019, sleep architecture

Published in Cureus. Sixty adults with insomnia were randomized 2:1 to 300 mg of ashwagandha root extract twice daily (600 mg total) or placebo for 10 weeks. Sleep onset latency, sleep efficiency, total sleep time, and wake-after-sleep-onset all improved versus placebo in both insomniac and healthy subgroups.^[8] Because cortisol regulation and sleep architecture are tightly coupled, elevated evening cortisol is a known driver of poor sleep onset — the sleep data and the cortisol data tell the same biological story from different angles.

Mechanism at a glance

What researchers say about cortisol and ashwagandha

Andrew Huberman, PhD, professor of neurobiology and ophthalmology at Stanford School of Medicine, on the cortisol rhythm, the HPA axis, and where ashwagandha fits in evening cortisol management. Episode #240, "How to Control Your Cortisol & Overcome Burnout," August 4, 2025. Dr. Huberman is not affiliated with YourHealthier and does not endorse this product.

KSM-66 vs. Sensoril vs. Shoden vs. generic root

Not all ashwagandha is the same molecule. Four forms dominate the clinical literature, and they differ in extraction method, plant part, withanolide concentration, and trial base.

Extract	Plant part	Withanolides	Clinical dose	Trial base
KSM-66 (Ixoreal Biomed)	Root only	≥5%	300–600 mg/day	24+ RCTs
Sensoril (Natreon)	Root + leaf	≥10%	125–250 mg/day	~10 RCTs
Shoden (Arjuna Natural)	Root + leaf	≥35% (glycoside)	120–240 mg/day	4+ RCTs
Generic powder	Variable	0.3–3% (unverified)	Unclear	0 (substitute studies)

KSM-66 has the deepest clinical evidence base of any ashwagandha extract. The Chandrasekhar 2012 cortisol study, the Wankhede 2015 strength trial, the Langade 2019 sleep trial, and the Coope 2026 athlete study all relied on KSM-66 as the active. Sensoril has its own legitimate evidence base, its higher withanolide concentration allows lower dosing, and it tends to be marketed for sleep. Shoden is the newest entrant, used in the Lopresti 2019 trial at 240 mg/day. Generic root powders, the kind in $8 Amazon bottles, vary so widely in withanolide content that they're basically uncharacterizable. ConsumerLab and Labdoor have repeatedly flagged generic ashwagandha products for inconsistent active content.

The honest critique — where the evidence is weaker than the headlines

The literature has three problems most product pages don't mention.

Cortisol moves but felt-stress doesn't always follow. The Albalawi 2025 meta-analysis showed cortisol dropped across seven trials but perceived stress on the PSS did not differ from placebo across six trials.^[2] If you take ashwagandha for 8 weeks and don't feel dramatically calmer, that doesn't mean it isn't working biologically. It means the biological effect and the subjective effect are partially separable. The hormonal change is the more reliable outcome. Plan accordingly.

Long-term safety beyond 12 weeks is undercharacterized in controlled trials. Most published RCTs ran 60–84 days. Fry, Fluck and Han (2022) published a case report describing reversible adrenal hypofunction in a 41-year-old woman after 10 weeks of ashwagandha supplementation at 858.6 mg/day, a reminder that any compound modulating the HPA axis can be overdone.^[9] Andrew Huberman recommends cycling ashwagandha, two weeks on, two weeks off — to avoid HPA-axis adaptation. Clinical trial protocols don't typically cycle, and trial outcomes remain positive at 8–12 weeks of continuous use, but the long-term continuous-use safety data isn't deep yet.

Heterogeneity across trials is moderate to high. Different extracts, different doses, different populations, different outcome scales. The 2025 Bachour meta-analysis ran a sensitivity analysis to confirm strongness, but no single dose-duration-extract protocol has been replicated enough to call it definitive. The current best practice is what the trials converge on: a standardized branded extract at 300–600 mg/day for at least 8 weeks.

How to take it

Dose: 300–600 mg/day of a standardized branded extract. KSM-66 at 600 mg/day is the most-studied protocol for cortisol reduction. Lower doses (250 mg) still show effects, with smaller magnitude than 600 mg, in the Salve dose-response trial.^[10]

Timing: Evening, for cortisol and sleep. Morning, for daytime energy and performance. The Chandrasekhar 2012 trial split the dose morning and evening. The Langade 2019 sleep trial used evening dosing. Both work. Pick the timing that matches your primary goal.

With food: Yes. Withanolides are lipophilic, absorption improves with a small amount of dietary fat. Most clinical trials specified "with meals." Our capsule also contains D3, which requires fat for absorption.

Duration: Plan for 8 weeks minimum before judging. Most trials show meaningful effects at 4 weeks and stronger effects at 8 weeks. Subjective effects can lag biological effects by 2–4 weeks.

Cycling: The trial literature doesn't require cycling. Huberman's recommendation (two weeks on, two weeks off) is precautionary, not evidence-based, there are no controlled trials testing cycling protocols against continuous use. We don't think cycling is necessary at the trial doses. We do think reassessment every 8–12 weeks is sensible.

Why we use KSM-66 in Ashwagandha Plus

When we built our Ashwagandha Plus formula, we picked KSM-66 because it has the deepest published trial base of any ashwagandha extract — 24+ RCTs covering stress, sleep, strength and testosterone,^[11] cognition, and reproductive health. The 600 mg/day dose matches the Chandrasekhar 2012 cortisol protocol exactly. We use Ixoreal-supplied raw material with batch certificates of analysis. We don't blend our KSM-66 with cheaper unstandardized root powder to lower the cost-per-bottle, which is a known industry practice that dilutes active content while keeping the label claim technically legal.

Full Supplement Facts panel:

Ingredient	Per serving (2 caps)	Role
KSM-66 Ashwagandha root extract (5% withanolides)	600 mg	Primary active, cortisol / HPA
L-Arginine	300 mg	Nitric oxide precursor
Maca root (Lepidium meyenii)	150 mg	Adaptogenic support
Panax Ginseng (root)	100 mg	Adaptogenic support
Shatavari (Asparagus racemosus)	50 mg	Ayurvedic rejuvenative
Vitamin D3 (cholecalciferol)	20 mcg (100% DV)	Hormonal cofactor
Vitamin B6 (pyridoxine HCl)	2.5 mg (147% DV)	Neurotransmitter cofactor
Vitamin B12 (methylcobalamin)	25 mcg (1042% DV)	Energy / nervous system

The supporting ingredients are intentionally at lower doses than their respective clinical thresholds. The primary effect, cortisol modulation — comes from the KSM-66. The L-Arginine, Maca, Ginseng, and Shatavari are at supporting doses because the trial literature on multi-ingredient stress formulas is much thinner than the single-ingredient ashwagandha literature, and we'd rather be honest about that than overstate the stacking claims.

Stacks that pair well

• Magnesium glycinate. Magnesium supports GABA signaling and sleep architecture from a different angle. The Schuster 2025 RCT confirmed bisglycinate improves subjective sleep quality, and the pairing covers two mechanistically distinct pathways. Take both in the evening. See Magnesium Glycinate for Sleep.
• Berberine. Elevated cortisol raises blood glucose. If you're managing both stress and metabolic markers, ashwagandha (evening) plus berberine (with meals) addresses different sides of the same problem. See Berberine Benefits.
• Lion's Mane — For people whose stress shows up as cognitive fog rather than sleep disruption. Lion's Mane supports nerve growth factor through a separate mechanism. See Lion's Mane Benefits.

Who should consider ashwagandha

• Adults under chronic, low-grade stress with flattened cortisol rhythm, particularly evening cortisol that won't come down for sleep
• People who've fixed the basics (sleep schedule, morning light, caffeine timing, exercise) and want a pharmacological lever for the residual HPA dysregulation
• Athletes during high-load training blocks, the Coope 2026 data specifically supports use during pre-season
• People with stress-related sleep onset latency — the Langade 2019 evidence applies directly here

Who should not take ashwagandha

• Pregnant or breastfeeding women. Animal studies suggest potential abortifacient effects at high doses. Contraindicated.
• People with autoimmune thyroid conditions (Hashimoto's, Graves'). Ashwagandha may stimulate thyroid hormone production. Consult an endocrinologist first.
• People on thyroid medication. Ashwagandha can alter thyroid hormone levels, medication dose may need adjustment.
• People on sedatives or anti-anxiety medication. GABAergic potentiation risk with benzodiazepines, barbiturates, other CNS depressants.
• People on immunosuppressants. Ashwagandha is immunomodulatory and may counteract immunosuppressive therapy.
• People scheduled for surgery. Discontinue at least 2 weeks before, potential interactions with anesthesia and sedation.
• Anyone with a history of adrenal insufficiency or post-traumatic stress disorder with low baseline cortisol. The Fry 2022 case report flagged this concern — additional cortisol suppression in already-low baselines is not the goal.

What does ashwagandha do?

Ashwagandha's strongest evidence is blunt: standardized extract has dropped cortisol by roughly 28% in randomized trials. It is an adaptogenic herb (Withania somnifera) that supports the stress response by regulating the HPA axis, the system that governs cortisol, with benefits building over four to eight weeks. It is sold as a dietary supplement and is not intended to diagnose, treat, cure, or prevent any disease.

How much ashwagandha per day?

Most clinical trials used 300 to 600 mg of a standardized root extract daily, often split into two doses. Benefits for stress and cortisol typically appear after several weeks of consistent use rather than the first dose. It is sold as a dietary supplement and is not intended to diagnose, treat, cure, or prevent any disease.

Does ashwagandha work?

For stress and cortisol support, the evidence is among the stronger of any adaptogen: multiple randomized, placebo-controlled trials show reduced cortisol and lower self-rated stress with daily standardized extract. Effects build over weeks and vary between individuals. It is sold as a dietary supplement and is not intended to diagnose, treat, cure, or prevent any disease.

Related reading

• Ashwagandha Benefits: 7 Evidence-Based Effects of KSM-66
• Ashwagandha for Sleep: Does KSM-66 Actually Help?
• KSM-66 vs Regular Ashwagandha: Why the Extract Matters
• Ashwagandha vs Rhodiola: Which Adaptogen Is Right for You?
• When to Take Ashwagandha: Morning or Night?
• Does Ashwagandha Cause Weight Gain? The Truth
• Ashwagandha for Men: Testosterone and Performance
• Ashwagandha for Women: Cortisol, Sleep, and Hormones
• Magnesium Glycinate for Sleep: 2026 Research
• Berberine Benefits: What the Research Shows

What is ashwagandha good for?

Ashwagandha is a plant used in Ayurvedic tradition for over 3,000 years. The root extract, particularly the KSM-66 standardized form, is the most clinically studied version, with 24+ published human trials. For the complete research overview, see ashwagandha benefits.

Does ashwagandha make you horny?

Some research suggests ashwagandha may support sexual function and libido, likely through cortisol reduction and modest testosterone support. The Lopresti 2019 trial found improvements in sexual well-being scores. However, it is not an aphrodisiac, and individual responses vary. See our ashwagandha for men article for the full data.

References

1. Bachour G, Samir A, Haddad S, Houssaini MA, El Radad M. Effects of Ashwagandha supplements on cortisol, stress, and anxiety levels in adults: a systematic review and meta-analysis. BJPsych Open. 2025;11(S1):S39. PMC
2. Albalawi AA. Dual impact of Ashwagandha: significant cortisol reduction but no effects on perceived stress, a systematic review and meta-analysis. Nutrition & Health. 2025;31(4):1395–1408. PubMed
3. Lopresti AL, Smith SJ, Malvi H, Kodgule R. An investigation into the stress-relieving and pharmacological actions of an ashwagandha (Withania somnifera) extract: a randomized, double-blind, placebo-controlled study. Medicine. 2019;98(37):e17186. PubMed
4. Coope OC, Otaegui E, Suárez M, Levington A, Abad-Sangrà M, Lloyd B, Spurr TJ, Roman-Viñas B. Ashwagandha root extract stabilises physiological stress responses in male and female team sports athletes during pre-season training. Nutrients. 2026;18(2):230. MDPI
5. Chandrasekhar K, Kapoor J, Anishetty S. A prospective, randomized double-blind, placebo-controlled study of safety and efficacy of a high-concentration full-spectrum extract of ashwagandha root in reducing stress and anxiety in adults. Indian Journal of Psychological Medicine. 2012;34(3):255–262. PubMed
6. Coope OC, Reales Salguero A, Spurr T, et al. Effects of root extract of ashwagandha (Withania somnifera) on perception of recovery and muscle strength in female athletes. European Journal of Sport Science. 2025;25(3):e12265. PubMed
7. Thanawala S, Shah R, Alluri KV, Bhupathiraju K, Desomayanandanam P, Bhuvenendran A. Efficacy and safety of Ashwagandha root extract sustained-release (AshwaSR) capsules in healthy adult, stressed subjects: a randomized, double-blind, placebo-controlled, parallel-group, 3-arm clinical trial. Medicine. 2026;105(11):e47990. PubMed
8. Langade D, Kanchi S, Salve J, Debnath K, Ambegaokar D. Efficacy and safety of ashwagandha (Withania somnifera) root extract in insomnia and anxiety: a double-blind, randomized, placebo-controlled study. Cureus. 2019;11(9):e5797. PubMed
9. Fry CH, Fluck D, Han TS. Adrenal hypofunction associated with ashwagandha (Withania somnifera) supplementation: a case report. Toxicology and Environmental Health Sciences. 2022;14(2):141–145. Springer
10. Salve J, Pate S, Debnath K, Langade D. Adaptogenic and anxiolytic effects of ashwagandha root extract in healthy adults: a double-blind, randomized, placebo-controlled clinical study. Cureus. 2019;11(12):e6466. PubMed
11. Wankhede S, Langade D, Joshi K, Sinha SR, Bhattacharyya S. Examining the effect of Withania somnifera supplementation on muscle strength and recovery: a randomized controlled trial. Journal of the International Society of Sports Nutrition. 2015;12:43. PubMed
12. Huberman A. How to control your cortisol & overcome burnout. Huberman Lab Podcast, Episode 240. August 4, 2025. Huberman Lab

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Disclosure: YourHealthier manufactures and sells the Ashwagandha Plus supplement discussed in this article. The cited research describes the ingredients and the published clinical trial literature, not specific claims about our product. Individual results vary. We earn revenue from product sales linked in this article.

*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.

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