Effect of Ashwagandha (Withania somnifera) extract on sleep: A systematic review and meta-analysis.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of randomized controlled trials
PubMed 34559859 · doi:10.1371/journal.pone.0257843
What was done
A systematic review and meta-analysis searched multiple databases (CENTRAL, MEDLINE, SCOPUS, Google Scholar, ClinicalTrials.gov, WHO Trials Portal, CTRI, and AYUSH) for randomized controlled trials evaluating Ashwagandha extract versus placebo on sleep in adults aged 18 and older. Primary outcomes were sleep quantity and sleep quality; secondary outcomes were mental alertness on rising, anxiety level, and quality of life. Two authors independently screened studies and extracted data.
What was found
Five randomized controlled trials totaling 400 participants were analyzed. Ashwagandha extract showed a small but significant improvement in overall sleep versus placebo (SMD -0.59; 95% CI -0.75 to -0.42; I² = 62%). Stronger effects were observed in subgroups with diagnosed insomnia, doses ≥600 mg/day, and treatment duration ≥8 weeks. Improvements were also found for mental alertness on rising and anxiety levels, with no significant effect on quality of life (numerical data for secondary outcomes not provided in abstract). No serious side effects were reported.
Why it matters
This review provides synthesized randomized evidence that Ashwagandha extract moderately improves sleep outcomes and reduces anxiety, particularly when dosed at 600 mg/day or higher for at least 8 weeks in individuals with insomnia.
Limits
The total sample size is small across only 5 trials (400 participants), with notable heterogeneity (I² = 62%). Quantitative effect estimates for secondary outcomes were not reported in the abstract, and evidence is insufficient to evaluate long-term safety.
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