Ashwagandha

Evidence ratingModerate

An adaptogen herb used in Ayurvedic medicine. Multiple RCTs have confirmed associations with reduced cortisol, improved sleep, and enhanced muscle strength — making it one of the better-researched natural supplements.

An ingredient with growing research

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Effects reported in research

Reduction in cortisol (significant decrease confirmed in studies)

Improved muscle strength and endurance (effects confirmed with resistance training)

Better sleep quality (improvements in onset and sleep efficiency suggested)

Association with reduced fatigue and improved recovery markers

Dosage & timing

300–600 mg/day of standardized extract (e.g., KSM-66).
Take before bed or with meals.
Effects often require 4–8 weeks to manifest.

Cautions

•Consult a doctor before use if you have thyroid disease, autoimmune conditions, or are pregnant.
•GI side effects (nausea, diarrhea) are occasionally reported.

Supporting research

Randomized controlled trial

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

An RCT in 57 healthy resistance-training men taking ashwagandha root extract (KSM-66) 600 mg/day for 8 weeks. Compared with placebo, bench press and leg extension strength improved significantly, alongside reduced serum cortisol, increased lean mass, and lower body fat. Limited by its short 8-week duration and a possible conflict of interest with the manufacturer.

View study details

Last checked: 2026-06-23