Sleep quality is now the clearest supported use on the page. Stress, anxiety, cortisol, cognition, exercise, testosterone, and metabolic claims all look more mixed under the current grading system than the old headline suggested. The supplement still has signal, but it is less top-heavy than the prior grading implied.
What the research says
Each row is a different health effect. A means the support looks strongest, B likely helpful, C mixed or modest, and — not enough human evidence yet.
Papers are individual studies. Research reviews summarize evidence from multiple studies, such as systematic reviews and meta-analyses.
B · Likely helpful
B
Stress & anxiety
16 of 22 scored papers positive, 0 null. Strongest single claim for ashwagandha. See featured health effect.
23 papers
B
Sleep quality
All 8 papers positive. The effect is stronger in adults with insomnia, at doses ≥600 mg/day, and over durations of 8+ weeks. Moderate improvement in overall sleep quality.
8 papers
B
Cortisol / HPA axis
7 of 10 papers show cortisol reduction. Most-cited meta-analysis reports a significant reduction of -1.16 µg/dL in serum cortisol.
10 papers
B
Cognition, memory & executive function
All 7 papers positive. Improvements reported on cognitive tasks, attention, and reaction time. Evidence is early-stage but directionally consistent.
7 papers
B
Immune function / inflammation
3 of 4 scored papers positive. Modest effects on inflammatory markers (CRP) and immune cell activity reported. Small evidence base.
8 papers
C · Mixed or limited evidence
C
Exercise performance & body composition
3 of 5 scored papers positive, 2 mixed. Improvements reported in strength (bench press, squat), cardiorespiratory fitness (VO₂ max), and recovery markers.
9 papers
C
Depression / mood
8 papers, 6 of them positive — but no qualifying meta-analysis or systematic review yet. Encouraging direction, waiting on review-level synthesis.
8 papers
— · Not enough human evidence yet
—
Testosterone / male hormones
Only 4 human papers — not enough to grade. Small-trial signal for testosterone elevation in men, but evidence is too thin and too industry-dependent to support the "testosterone booster" marketing.
4 papers
—
Thyroid function (TSH, T3, T4)
Only 3 papers. Some signal for normalizing subclinical hypothyroidism — but not enough evidence for a grade.
3 papers
—
Cardiovascular markers / lipids
3 papers. Limited data on lipid profile or blood pressure effects.
3 papers
—
Male fertility / sperm parameters
Only 1 paper. Not enough to assess.
1 paper
—
Blood glucose / insulin / diabetes
Only 1 paper. Not enough to assess.
1 paper
Quick facts
Dose, form, and context from the 85 records in the database.
Typical dose
300–600 mg/day of standardized root extract
Best taken
Morning or split between morning and evening. With or without food
Form
Standardized root extracts (KSM-66, Sensoril, Shoden) dominate trials. Withanolide content is the active marker
Common side effects
Mild drowsiness, stomach discomfort. Rare cases of liver injury reported with prolonged high-dose use
Drug interactions
May amplify the effect of sedatives, thyroid medications, and immunosuppressants. Avoid in pregnancy
Duration for effect
Most trials run 8–12 weeks. Stress and anxiety effects appear within 2–4 weeks
Industry caveat
Most positive trials use proprietary standardized extracts. Generic ashwagandha capsules may not match trial results
Quality-verified products
Products that pass third-party quality testing.
Coming soon
Quality-verified ashwagandha products will be listed with third-party purity testing and verified standardization. Given the evidence picture, this site will recommend ashwagandha primarily for stress, anxiety, and sleep — where the data is strongest — and not for the testosterone or performance claims that dominate some marketing.
How we graded Ashwagandha
Grades come from 43 unique research papers indexed from PubMed — including 8 meta-analyses, 6 systematic reviews, and 29 randomized trials. Most trials use proprietary standardized extracts (KSM-66, Sensoril, Shoden) where results vary by extract type. Generic ashwagandha may not match trial results. Each supplement is graded by health effect using a certainty × effect matrix applied across PubMed evidence per health effect. Cochrane reviews and high-quality systematic reviews carry the most weight. From abstract-only data, "high certainty" is rare — most A grades come from moderate certainty plus consistent meaningful-positive evidence. See Methodology for full detail.