Ashwagandha for Stress, Anxiety, and Sleep: Evidence Summary
Ashwagandha (Withania somnifera) demonstrates moderate efficacy for reducing stress and anxiety in generally healthy adults, with emerging evidence supporting modest improvements in sleep quality, though it is not endorsed by major clinical guidelines for insomnia management.
Efficacy for Stress and Anxiety
Meta-analysis of 12 randomized controlled trials (n=1,002 participants) shows ashwagandha significantly reduces anxiety (SMD: -1.55,95% CI: -2.37 to -0.74) and stress levels (SMD: -1.75,95% CI: -2.29 to -1.22) compared to placebo. 1
Dose-response analysis indicates optimal effects for anxiety at doses up to 12,000 mg/day and for stress at 300–600 mg/day. 1
In an 8-week randomized trial of 60 stressed adults, ashwagandha 250 mg/day and 600 mg/day both significantly reduced Perceived Stress Scale scores (P<0.05 and P<0.001, respectively) and serum cortisol levels (P<0.05 and P<0.0001, respectively) compared to placebo. 2
A 30-day trial (n=60) demonstrated that ashwagandha 225 mg/day significantly reduced salivary cortisol levels from baseline to day 15 and day 30, while placebo showed non-significant cortisol increases. 3
Efficacy for Sleep Quality
Systematic review and meta-analysis of 5 randomized controlled trials (n=400) found ashwagandha extract produced a small but significant improvement in overall sleep (SMD: -0.59,95% CI: -0.75 to -0.42). 4
Subgroup analysis revealed more prominent sleep benefits in adults diagnosed with insomnia, at doses ≥600 mg/day, and with treatment duration ≥8 weeks. 4
The 8-week trial of stressed adults reported significant improvement in sleep quality with both ashwagandha 250 mg/day and 600 mg/day compared to placebo. 2
Ashwagandha also improved mental alertness on rising but showed no significant effect on quality of life measures. 4
Efficacy for Cognitive Function
- A 30-day trial demonstrated significant improvements in cognitive flexibility, visual memory, reaction time, psychomotor speed, and executive functioning with ashwagandha 225 mg/day and 400 mg/day compared to placebo (P<0.05). 3
Safety Profile
No serious adverse events were reported across clinical trials reviewed; only mild and transient side effects occurred, including somnolence, epigastric discomfort, and loose stools (>5% incidence). 5
Less common adverse events (<5%) included dizziness, drowsiness, nasal congestion, nausea, constipation, dry mouth, and skin rash. 5
Preclinical chronic toxicity studies up to 8 months found ashwagandha root extracts to be safe, with no mutagenicity or genotoxicity reported. 5
Long-term safety data remain limited, and more extensive safety studies are needed to assess prolonged use. 4
Guideline Context and Clinical Positioning
Major clinical guidelines (American Academy of Sleep Medicine, American College of Physicians, American Geriatrics Society) do not list ashwagandha as a recommended treatment for insomnia or anxiety disorders. 6, 7
Evidence-based insomnia guidelines explicitly state that herbal supplements lack sufficient efficacy and safety data to support routine use. 6
Cognitive Behavioral Therapy for Insomnia (CBT-I) remains the first-line treatment for chronic insomnia, with superior long-term efficacy and sustained benefits after discontinuation compared to any pharmacologic or herbal intervention. 6, 7
Practical Considerations
The certainty of evidence for ashwagandha's effects on stress and anxiety is rated as low, indicating that further high-quality studies are needed to firmly establish clinical efficacy. 1
Ashwagandha may serve as an adjunctive option for stress reduction and mild sleep disturbances in adults who prefer herbal approaches, but it should not replace evidence-based behavioral therapies or FDA-approved medications when clinically indicated. 2, 4
Optimal dosing appears to be 300–600 mg/day for stress and ≥600 mg/day for sleep, with treatment duration of at least 8 weeks to achieve meaningful benefits. 1, 4
Common Pitfalls to Avoid
Do not recommend ashwagandha as a substitute for CBT-I in patients with chronic insomnia, as behavioral therapy provides more durable and evidence-based benefits. 6, 7
Avoid using ashwagandha in place of FDA-approved medications for clinically significant anxiety disorders or insomnia requiring pharmacotherapy. 6
Do not assume long-term safety based on short-term trial data; counsel patients that extended use beyond 8–12 weeks lacks robust safety documentation. 4, 5