Ashwagandha (Withania Somnifera) Clinical Evidence

Journal of the American Nutraceutical Association

Biswajit A, et al. A standardized Withania somnifera extract significantly reduces stress-related parameters in chronically stressed humans: a double-blind, randomized, placebo-controlled trial. 2008;11(1):50-56.

What effect does Ashwagandha have on stress?

Ashwagandha has a long history of use in Asia for stress-related health conditions. How does it affect various parameters of stress?

Study Type:
Human clinical intervention trial

Study Design:
Double-blind, randomized, placebo-controlled. Participants took either 125 or 250 mg of Ashwagandha root and leaf extract twice a day for 8 weeks. Researchers measured stress levels using the modified Hamilton Anxiety Scale (mHAM-A) at baseline, 30 days, and 60 days. Biochemical measures of stress were measured at baseline and 60 days.

130 chronically stressed people (98 completed the study)

125/day, 125 mg twice daily, or 250 mg twice daily, for 8 weeks

Between day 0 and 60, the group taking 125 mg/day saw significant decreases in the following parameters (compared to placebo):

  • Mean mHAM-A score
  • Serum cortisol (a stress hormone)
  • Serum CPR (a marker of inflammation)
  • Pulse rate
  • Blood pressure

In addition, the following parameters rose significantly:

  • Serum DHEAS (a sex hormone lowered by stress)
  • Hemoglobin (a component of red blood cells which delivers oxygen to cells, supporting normal energy levels)

In the higher-dose treatment groups there were even greater, dose-dependent changes in the parameters above. Additionally, the following parameters fell: 

  • Blood glucose
  • Serum lipids
  • Cardiac risk ratio

At 30 and 60 days, all treated groups showed improvement in mHAS scores with reduction in the following symptoms of stress:

  • Fatigue
  • Flushing and perspiration
  • Loss of appetite
  • Headache and muscle pain
  • Feelings of impending doom
  • Palpitations
  • Dry mouth
  • Sleeplessness
  • Forgetfulness
  • Irritability
  • Inability to concentrate

There were no adverse effects.

“Together these findings suggest that WSE use might contribute to decreased risk of chronic disease, an idea meriting further investigation.”


Salve J, et al. Adaptogenic and anxiolytic effects of Ashwagandha root extract in healthy adults: a double-blind, randomized, placebo-controlled clinical study. 2019 Dec 25;11(12):36466.

Can Ashwagandha reduce symptoms of stress and improve sleep?

Stress, anxiety, and sleep disturbances are all precursors to chronic disease. Can Ashwagandha, an adaptogenic Ayurvedic herb, help ease symptoms of stress that undermine health?

Study Type:
Human clinical intervention trial

Study Design:
Prospective, randomized, double-blind, placebo-controlled. Participants took 125 mg or 300 mg of a highly concentrated Ashwagandha root extract, or placebo, twice a day for 8 weeks. Researchers used the Perceived Stress Scale (PSS) to measure stress at baseline, 4 weeks, and 8 weeks, and the Hamilton Anxiety Scale (HAM-A) and serum cortisol to measure anxiety at baseline and 8 weeks. Sleep quality was assessed using a 7-point scale.

125 mg twice daily or 300 mg twice daily, for 8 weeks

60 male and female volunteers with moderate to high stress. (58 completed study)

Scores on the PSS and serum cortisol were significantly reduced in both the lower and higher dose treatment groups. Participants taking Ashwagandha also had significant improvement in sleep quality, compared to placebo.

“Ashwagandha root aqueous extract was beneficial in reducing stress and anxiety.”

Mechanism of Action

Ashwagandha lowers cortisol (a stress hormone) and increases the activity of serotonin, a neurotransmitter that helps regulate mood. Animal research suggests it may also influence GABA, an inhibitory neurotransmitter. Ashwagandha may work by moderating the hypothalamic-pituitary axis (HPA), disturbances of which are linked to depression and anxiety. Other possible mechanisms include Ashwagandha’s antioxidant and anti-inflammatory effects, as both oxidative stress and inflammation are implicated in mood disorders.