Ashwagandha

In a double-blind trial in India, 60 patients with insomnia and anxiety were randomised 2:1 to 300 mg of root extract or placebo twice daily for 10 weeks, with sleep measured by actigraphy (a wrist-worn movement sensor); 58 completed. At 10 weeks, sleep onset latency was 29.00 minutes with ashwagandha and 33.94 minutes with placebo (p = 0.019); sleep efficiency rose from 75.63 to 83.48 with ashwagandha and from 75.14 to 79.68 with placebo; and sleep quality (p = 0.002) and anxiety scores also improved more with ashwagandha [1]. A second trial gave 150 healthy adults with non-restorative sleep 120 mg of a standardised extract or placebo once daily for 6 weeks; 144 completed, self-reported sleep quality rose 72% with ashwagandha against 29% with placebo (p < 0.001), and actigraphy showed improvements in sleep efficiency, total sleep time, sleep latency and wake after sleep onset [3]. A 2021 meta-analysis of 5 randomised trials with 400 participants found a small but significant effect on overall sleep (standardised mean difference -0.59, 95% CI -0.75 to -0.42), larger in adults diagnosed with insomnia, at doses of 600 mg a day or more, and with treatment of 8 weeks or longer [4].

The trials are few and small, last 6 to 10 weeks, and use different extracts and doses [4, 1, 3]. The meta-analysis found moderate heterogeneity between trials (I-squared 62%) and noted that data on serious adverse effects are limited, so long-term safety has not been established [4]. The effects build over weeks of daily use, consistent with an action on the stress-hormone system rather than acute sedation.

The insomnia and anxiety trial used 300 mg of root extract twice daily for 10 weeks [1]; the non-restorative sleep trial used 120 mg of standardised extract once daily for 6 weeks [3]; and the stress trial used 300 mg twice daily for 60 days [2]. In the meta-analysis, larger effects were seen at 600 mg a day or more [4].