# The Ancient Herb Backed by Modern Science

Published March 2026 • 5 min read
Tweet Share

### Key Takeaways

- KSM-66 extract reduced cortisol by 27.9% in clinical trials
- Improves sleep quality, especially in people with insomnia
- Increases testosterone by 14.7% in healthy men
- 300-600mg daily of root extract is the evidence-based dose

Ashwagandha has been used in Ayurvedic medicine for 3,000 years. Unlike most traditional remedies, it actually has impressive clinical trial data behind it. Multiple randomised, double-blind, placebo-controlled studies show meaningful effects on stress, sleep, hormones, and physical performance.

## What the Trials Show

The most robust evidence is for stress reduction. A landmark study using KSM-66 ashwagandha extract showed a 27.9% reduction in serum cortisol levels compared to placebo over 60 days. Participants also reported significant reductions in perceived stress, anxiety, and insomnia. These aren't marginal effects — they're clinically meaningful.

For testosterone, a study in the American Journal of Men's Health found that 600mg of ashwagandha root extract increased testosterone by 14.7% and DHEA-S by 18.2% in healthy men over 8 weeks. Fertility studies show significant improvements in sperm count, motility, and quality. For women, ashwagandha improves sexual function without affecting hormones negatively.

## How It Works

Ashwagandha's primary active compounds — withanolides — modulate the HPA (hypothalamic-pituitary-adrenal) axis, which controls your stress response. By calming this axis, ashwagandha reduces cortisol output and helps your body return to baseline faster after stress. It also has GABAergic effects, promoting calm without sedation.

Beyond stress, ashwagandha has anti-inflammatory and antioxidant properties. It inhibits NF-kB (a master inflammatory switch), reduces C-reactive protein, and scavenges free radicals. There's also emerging evidence for neuroprotective effects — it promotes nerve growth factor (NGF) production and may help with memory and cognitive function.

## How to Take It

Use a standardised root extract — KSM-66 or Sensoril are the most studied brands. Dose: 300-600mg daily. For stress and cortisol reduction, take it in the evening. For physical performance and testosterone, morning dosing works well. It can be taken with or without food.

Most people notice effects within 2-4 weeks, with maximum benefits at 8-12 weeks. Ashwagandha is generally safe, but it can interact with thyroid medications (it may increase thyroid hormone levels), immunosuppressants, and sedatives. People with autoimmune conditions should consult their doctor, as it can stimulate immune activity. Cycle it — 8 weeks on, 2-4 weeks off — to maintain sensitivity.

#### Who Is This For?

Anyone interested in evidence-based longevity strategies, health optimisation, and understanding the latest research on ageing and healthspan.

#### Consult Your Doctor If...

You are pregnant, breastfeeding, taking prescription medications, or have a pre-existing medical condition. This content is educational and does not replace professional medical advice.

### Go Deeper

Ready to learn more? These guides break it all down:

Top 8 Compounds Deep Dive Best Longevity Stack Best Anti-Aging Compared Take the Longevity Quiz

### Get Longevity Insights Weekly

Join thousands getting science-backed health tips every week.

Medical Disclaimer: This content is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare provider before starting any new supplement or making changes to your health regimen.

#### Sources & References

1. Indian Journal of Psychological Medicine - KSM-66 and Cortisol
2. American Journal of Men's Health - Ashwagandha and Testosterone
3. Journal of Ethnopharmacology - Ashwagandha Withanolides Review
4. Cureus - Ashwagandha Root Extract and Sleep Quality