Ashwagandha
Ashwagandha (Withania somnifera) is an adaptogenic herb with a long history in Ayurvedic medicine. It contains withanolides as its primary bioactive compounds and is widely studied for its effects on stress resilience, cortisol modulation, and cognitive function.
Expert Evidence
25 references from 4 experts
“Ashwagandha is known to lower anxiety and cortisol. I'm not going to take ashwagandha year round. I would only do this if I was feeling like I wasn't managing my short and medium-term stress well. I don't take it on a regular basis, I do take it when things are particularly stressful.”
Tools for Managing Stress & Anxiety | Huberman Lab Essentials
30:489 references in 6 episodes from 2021–2025
Huberman views ashwagandha as the top supplement-based adaptogen for reducing cortisol and anxiety, backed by strong clinical evidence showing 14.5-27.9% cortisol reduction. However, he uses it only situationally during high-stress periods and cautions against continuous use beyond two weeks without breaks.
Consumption
Huberman does not take ashwagandha regularly — he uses it only during particularly stressful periods rather than year-round.
Benefits
Ashwagandha has powerful anxiolytic effects and strong cortisol-reducing properties (14.5-27.9% reduction in stressed individuals), with mild antidepressant effects likely linked to stress reduction. Huberman ranks it at the top of supplement-based adaptogens.
Best Practices
Huberman recommends 250-300mg twice daily, with the first dose in early afternoon and the second in the evening, avoiding morning dosing to preserve the natural cortisol awakening response needed for daytime energy.
Cautions
Huberman cautions against using ashwagandha for longer than two-week periods without taking breaks and does not recommend routine daily use.
“There's certain supplements that I use to sleep as well. I'm a fan of glycine, ashwagandha, magnesium L-threonate.”
Dr. Peter Attia on Mastering Longevity – Insights on Cancer Prevention, Heart Disease, and Aging
3:45:431 reference in 1 episode from 2023
Rhonda Patrick includes ashwagandha as part of her sleep supplement routine, alongside glycine and magnesium L-threonate. She confirms personal use but provides no specific dosage, brand, timing, or discussion of mechanisms or cautions.
“A meta-analysis published in 2024 pulled together data from nine randomized control trials and showed a significant positive effect of ashwagandha on perceived stress, anxiety, and cortisol levels in the blood.”
Ashwagandha Fails in New Study
5:4213 references in 4 episodes from 2020–2025
Brad Stanfield acknowledges ashwagandha's strong evidence base for reducing stress, anxiety, and improving sleep, but personally stopped taking it after not noticing benefits. He warns about potential liver injury and thyroid effects, and advises staying within studied dosage ranges due to limited long-term safety data.
Benefits
Multiple meta-analyses show ashwagandha significantly reduces stress, anxiety, and cortisol while improving sleep quality, cognitive performance, and physical performance metrics including VO2 max and strength. It also increases testosterone in males and DHEA levels.
Best Practices
Recommends 250-600mg daily, advising against exceeding 600mg due to insufficient long-term data. Suggests taking it at night given its sleep-supporting mechanism.
Cautions
Ashwagandha has been linked to acute liver injury in case reports and may affect thyroid function. Experts advise against use during pregnancy. Stanfield personally stopped taking it after not noticing meaningful benefits for anxiety or sleep, as he doesn't struggle with those issues.
“If you look at things like ashwagandha, very similar types of research. It's not that these things will take your resting HRV and make it get better, but what it will do is it helps you not be as responsive to a stressful stimuli. That is the true benefit. Whether this is high-intensity exercise or a psychological stressor, ashwagandha may blunt how much of an impact those things make on you. Kind of stress inoculators, if you will.”
Enhance Your Physical & Mental Resilience (HRV, Respiratory Rate, RHR)
1:29:362 references in 2 episodes
Galpin views ashwagandha as a stress-buffering supplement, explaining it doesn't improve baseline HRV but blunts the impact of physical and psychological stressors—acting as a "stress inoculator." He specifically recommends the KSM-66 form for improving stress and cognitive function in people with chronic sleep or stress issues. No personal use is mentioned, no dosing guidance is provided, and no cautions are discussed.
Side Effects
- Drowsiness or sedation
- Gastrointestinal discomfort
- Possible thyroid hormone elevation with prolonged use
- Headache in some individuals
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