Ashwagandha (Withania somnifera) for Stress, Sleep, and Cognitive Health: What the 2025 Evidence Really Says

Key Takeaways

A 2025 Nutrients review concludes that standardized ashwagandha extract can reduce perceived stress/anxiety, improve sleep quality, and enhance several measures of cognitive performance in adults—though many trials remain small and short.

• Effective study doses typically range 225–600 mg/day of standardized extract for 4–12 weeks.

• Safety matters: rare but documented cases of cholestatic liver injury have been linked to ashwagandha; avoid use if pregnant, with hyperthyroidism, or certain prostate cancers, and use caution with sedatives/antidepressants.

• Ashwagandha is not a substitute for care; it may be a supportive tool—especially for shift workers—when folded into sleep hygiene, light timing, and behavioral strategies.

Why Ashwagandha—and Why Now?

Rates of stress, poor sleep, and mood symptoms remain high worldwide. The WHO estimates ~280 million people lived with depression in 2019, underscoring the demand for safe, effective adjuncts to standard care. World Health Organization

Enter Withania somnifera (ashwagandha)—an Ayurvedic “rasayana.” Its bioactives (notably withanolides) appear to modulate stress pathways (e.g., HPA axis) and neuroinflammation, aligning with reported benefits in stress, sleep, and cognition. The 2025 Nutrients review by Wiciński et al. synthesizes clinical and preclinical data across these domains.

What the 2025 Review Found

1) Stress, Anxiety & Mood

Across randomized trials, standardized extracts have been associated with lower perceived stress/anxiety and reduced morning cortisol—consistent with HPA-axis modulation. Effects sizes vary; many studies are small (weeks to a few months). MDPI+1

• Meta-analyses report significant improvements vs placebo on tools like HAM-A and PSS, with generally mild side effects; authors still call for larger, longer studies. PMC

Bottom line: Promising for stress relief, but durability beyond ~12 weeks and comparative efficacy vs first-line pharmacotherapy remain uncertain. MDPI

2) Sleep Quality & Fatigue

Multiple RCTs (4–12 weeks) show improvements in sleep onset latency, total sleep time, sleep efficiency, refreshed awakening, and daytime alertness—with a dose-response signal around 600 mg/day in some cohorts. MDPI+1

• A 2024 trial (225 mg) reported better attention, vigilance, and reduced perceived fatigue in younger adults, complementing sleep findings. MDPI

Bottom line: For insomnia-like complaints and nonrestorative sleep—especially in high-stress schedules (hello, night shift)—ashwagandha shows consistent, if modest, benefits. MDPI

3) Cognitive Function & Memory

Trials in healthy adults (225–600 mg/day) report gains in recall memory, reaction time, complex attention, executive function, and processing speed vs placebo. Early studies in mild cognitive impairment show signals, but sample sizes are small. MDPI

Bottom line: Supportive data suggest attention/processing benefits; we still need larger, longer head-to-heads and standardized extracts. MDPI

Dosing, Forms & How to Use (Based on the Literature)

• Typical clinical range: 225–600 mg/day standardized extract (often KSM-66®/Sensoril®-class products) for 8–12 weeks, sometimes split twice daily. MDPI+1

• Timing: If targeting sleep, many protocols include an evening dose. If focusing on daytime calm/focus, split AM/PM. (Follow product standardization.) MDPI

• Stacking: Pair with sleep hygiene, light timing, caffeine cut-off, and consistent wake time—especially critical for shift workers. (Mechanistic alignment with HPA circadian dynamics.) MDPI

Clinical pearl for shift workers: Consider a two-week “on” trial at 300–600 mg/day while tightening sleep anchors (fixed wake time on off-days, strategic light exposure) to gauge personal signal before committing to longer courses. MDPI

Safety, Interactions & Who Should Avoid It

While many participants tolerate ashwagandha in trials, case reports and series associate it with cholestatic or mixed-pattern liver injury (jaundice, pruritus), typically resolving after discontinuation but occasionally severe. PubMed+2PMC+2

Use caution or avoid if:

• Liver disease or unexplained jaundice history. PubMed+1

• Hyperthyroidism (possible T3/T4 increases, symptom worsening). MDPI

• Hormone-sensitive prostate cancer (possible testosterone effects). MDPI

• Pregnant/trying to conceive (high-dose risks; avoid unless clinician-supervised). MDPI

Drug interactions to discuss with your clinician/pharmacist:

• Sedatives, benzodiazepines, barbiturates, anticonvulsants (additive CNS effects).

• SSRIs/SNRIs/other antidepressants (case-level reactions reported; possible CYP3A4/CYP2D6 interactions). MDPI

If you notice itching, dark urine, right-upper-quadrant pain, or jaundice, stop immediately and seek care. PubMed+1

Evidence Gaps the 2025 Review Highlights

• Standardization: Withanolide content and extract types vary; better assay/labeling is needed to compare trials. MDPI

• Duration & size: Many studies are ≤12 weeks with small N; we need longer safety and head-to-head trials vs standard therapies. MDPI

• Populations: Limited data in poly-medicated elders, endocrine disorders, or pregnancy. MDPI

Practical Protocol (Education, Not Medical Advice)

1. Screen: meds, pregnancy plans, thyroid/liver history. (If yes, talk to your clinician.)

2. Pick a standardized product (clear withanolide %; reputable brand). MDPI

3. Start low (e.g., 225–300 mg/day), reassess at 2–4 weeks; consider up to 600 mg/day if well-tolerated and still symptomatic. MDPI

4. Stack behaviors: consistent sleep/wake, dark room, timed light, caffeine cut-off, brief daytime movement.

5. Stop if adverse effects (especially hepatic or hyperthyroid symptoms). PubMed

FAQs (People Also Ask)

Is ashwagandha proven to work? Evidence supports modest improvements in perceived stress/anxiety, sleep quality, and several cognitive measures vs placebo; trials tend to be short and small. MDPI

How long until I feel effects? Some report changes within 2–4 weeks, with many RCTs running 8–12 weeks. MDPI

What’s the best dose? Most trials use 225–600 mg/day standardized extract. For sleep, ~600 mg/day often shows the strongest signal. MDPI

Can it help if I work nights? It may support sleep quality and next-day alertness, but you’ll get the most benefit by pairing it with circadian-friendly routines (light, caffeine timing, sleep schedule). MDPI

Is ashwagandha safe for everyone? No. Avoid in pregnancy, hyperthyroidism, some hormone-sensitive cancers, and use caution with liver disease or CNS-active meds. PubMed

For Nurses & Shift Workers: A Smart Way to Trial Ashwagandha

• Week 0: Clear with your clinician (med list + conditions).

• Weeks 1–2: 225–300 mg/day; anchor wake time, block morning light after nights, schedule a 20–30-min “wind-down” ritual.

• Weeks 3–6: If needed, titrate toward 600 mg/day, maintain sleep anchors, track PSQI or a simple sleep log for objective signal. MDPI

Citations & Further Reading

• Wiciński M, et al. Ashwagandha and Its Effects on Well-Being—A Review. Nutrients 2025;17(13):2143. (Publisher & PMC records). MDPI+1

• Leonard M, et al. Acute and Repeated Ashwagandha Supplementation and cognitive outcomes. Nutrients 2024;16(12):1813. MDPI

• Björnsson HK, et al. Ashwagandha-induced liver injury: case series. Liver Int. 2020. PubMed+1

• Lubarska M, et al. Ashwagandha-induced liver injury: case report. Cureus 2023/2024. PMC+1

• WHO Depression fact sheet (global prevalence context). World Health Organization

Author: R.E. Hengsterman, MSN, MA, M.E., RN

Registered nurse, night-shift administrator, and author of The Shift Worker’s Paradox

Nursewhowrites.com

For educational purposes only. Not medical advice.