Ashwagandha root extract for improving cognitive function, stress, happiness, and sleep quality in individuals with stress Original paper

Supplementation with a sustained-release ashwagandha root extract product improved some aspects of cognitive function — as well as perceived stress, happiness, and sleep quality — in healthy men and women with moderate levels of perceived stress.

This Study Summary was published on January 4, 2022.


Chronic stress and stress hormones may negatively affect cognitive abilities, sleep, and psychological well-being. Some research suggests that the root extract of ashwagandha, an herb commonly used in Ayurveda practices, may reduce stress and stress hormones, and it may also improve cognitive function, sleep, and quality of life. This trial examined these potential effects.

The study

In this 90-day randomized controlled trial, 125 healthy men and women, aged 20–55 years with moderate levels of perceived stress, took capsules containing either 300 milligrams of sustained-release ashwagandha root extract (Prolanza™) or a placebo.

The primary outcome was cognitive function measured using the Cambridge Neuropsychological Test Automated Battery (CANTAB). The secondary outcomes were perceived stress, serum cortisol levels, happiness (measured with the Oxford Happiness Questionnaire), sleep quality (measured with the Pittsburgh Sleep Quality Index), and levels of serum brain-derived neurotrophic factor (a neurotrophin that plays important roles in cognitive performance and brain morphology developments).

The results

Recall memory (an aspect of cognitive function) improved with ashwagandha by 19% but did not change with placebo, and the differences between groups at the end of the intervention were statistically significant.

The total error rate in recalling patterns (another aspect of cognitive function) nonsignificantly improved by 25% with ashwagandha and nonsignificantly worsened with placebo by 29%, and the differences between groups at the end of the intervention was statistically significant.

The secondary outcomes of perceived stress, serum cortisol levels, happiness, and sleep quality improved more with ashwagandha, compared to placebo.


It’s worth noting that the trial was funded by Inventia Healthcare Ltd. and Laila Nutraceuticals (the manufacturers of Prolanza™) and that some of the researchers were employees of these companies at the time of the study.

The authors did not report total CANTAB scores and focused on discussing the positive findings. Also, CANTAB is a scale designed to measure cognitive dysfunction in patients with various neurological conditions,[1] and some research suggests that CANTAB may not be able to accurately measure cognitive function in healthy adults.[2] Therefore, it is possible that CANTAB is not a good measure of cognitive function in healthy adults.

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This Study Summary was published on January 4, 2022.