In a 60-day randomized, double-blind, placebo-controlled study, participants received either a placebo or 240 mg standardized Ashwagandha extract. Compared with the placebo, individuals who took Ashwagandha reported a better mood and lower stress levels, as well as less anxiety. Testing also confirmed lower morning cortisol levels for the Ashwagandha group. The study, published in 2019, suggested a connection between the HPA axis and Ashwagandha’s active compounds, but the authors called for additional research.
Additional randomized, double-blind, placebo-controlled studies have further examined standardized Ashwagandha extracts in chronically stressed adults. In one 60-day clinical trial using a root-and-leaf extract (Shoden®), participants experienced dose-dependent reductions in perceived stress, cortisol, and other physiological stress markers, without reported adverse effects.
A separate eight-week study using a similar standardized extract (Sensoril®) found significant reductions in perceived stress at doses as low as 125 mg per day, supporting Ashwagandha’s role in modulating the HPA axis.
Also in 2019, an eight-week, prospective, randomized, double-blind, placebo-controlled study examined the impact of varied doses of a highly concentrated Ashwagandha extract. A total of 60 men and women with self-reported “moderate stress” levels randomly received 125 mg Ashwagandha, 300 mg Ashwagandha or a placebo twice daily. The two Ashwagandha groups saw a “significant reduction” in their perceived stress levels — and reported significant improvements in sleep quality.
In 2017, a prospective, randomized, double-blind, placebo-controlled study tested one of Ashwagandha’s traditional uses in Ayurveda. Researchers gave either Ashwagandha extract (300 mg twice daily) or placebo to 50 adults with mild cognitive issues. After eight weeks, the subjects who took Ashwagandha showed significant improvements in both general and immediate memory. They also saw improvements in information processing speed, attention and executive function.
A randomized, double-blind, placebo-controlled study published in 2020 looked at Ashwagandha’s impact on sleep in adults aged 65 to 80. Participants received either a placebo or 600 mg Ashwagandha daily for 12 weeks. The Ashwagandha group reported significant improvements in sleep, mental alertness the next day and overall well-being compared with the placebo recipients.
According to a 2021 systematic review and meta-analysis, Ashwagandha exerts a significant yet small impact on sleep (as well as anxiety levels), while improving daytime alertness. The analysis examined five randomized controlled trials with 400 total participants. It also improved alertness upon rising from bed.
Additionally, Ashwagandha has been used to stimulate the thyroid. A prospective, randomized, double-blind, single-center placebo-controlled study published in 2017 gave 50 subclinical hypothyroid patients ages 18 to 50 either 600 mg Ashwagandha extract or a placebo. All participants had elevated levels of thyroid stimulating hormone. After two months, those who received Ashwagandha had normalized levels of TSH, while the placebo group did not see those same positive changes.
A 2020 research review assessed Ashwagandha’s impact on various brain disorders (including anxiety, Alzheimer's, Parkinson's, schizophrenia, Huntington's disease, dyslexia, depression, autism, addiction, amyotrophic lateral sclerosis, attention deficit hyperactivity disorder and bipolar disorders). The review concluded that Ashwagandha offers “extensive potential” as a neuroprotective, with support from preclinical studies, clinical trials and published patents. Additionally, the herb is considered to be “healthy, safe and dependable.” However, researchers acknowledged there is a “vague understanding of the mechanistic pathways involved,” and they urged further study.
