Ashwagandha: Benefits, Dosage & When to Take

Ashwagandha (Withania somnifera) is an ancient medicinal herb that has been used in Ayurvedic medicine for over 3,000 years. In recent years, it has become one of the most popular supplements in the Western world, driven by a growing body of clinical research supporting its effects on stress, anxiety, sleep, physical performance, and hormonal health.

Classified as an adaptogen — a substance that helps the body resist and adapt to stress — ashwagandha works primarily by modulating the hypothalamic-pituitary-adrenal (HPA) axis, which governs your cortisol response. In practical terms, this means it can help take the edge off chronic stress without the sedation of prescription anti-anxiety medications.

What sets ashwagandha apart from many herbal supplements is the quality of the research behind it. Multiple randomized, double-blind, placebo-controlled trials have demonstrated meaningful benefits, making it one of the more evidence-supported adaptogenic herbs available.

What are the key benefits?

• Stress and anxiety reduction. This is ashwagandha's strongest claim. A systematic review of clinical trials found that ashwagandha supplementation significantly reduces perceived stress and cortisol levels. In one well-cited study, participants taking 600 mg of ashwagandha root extract daily experienced a 30% reduction in cortisol compared to placebo.

• Improved sleep quality. Ashwagandha has been shown to improve both sleep onset and sleep quality, particularly in people experiencing stress-related insomnia. The active compound triethylene glycol may contribute to its mild sedative effects. Its Latin name, "somnifera," literally means "sleep-inducing."

• Physical performance and body composition. Research suggests that ashwagandha can increase VO2 max, improve muscular strength and recovery, and support healthy testosterone levels in men. One study found that men taking ashwagandha during a resistance training program gained significantly more muscle mass and strength compared to placebo.

• Cognitive function. Some studies indicate that ashwagandha improves reaction time, attention, and memory. These benefits may be partly due to its stress-reducing effects — when cortisol is lower, cognitive function often improves.

• Thyroid support. Ashwagandha may support thyroid function by mildly increasing T3 and T4 hormone levels. This can be beneficial for people with subclinical hypothyroidism, but it also means people with hyperthyroidism or those on thyroid medication should exercise caution.

What is the recommended dose?

Most clinical trials use doses between 300 and 600 mg per day of a standardized root extract. The two most well-studied branded extracts are:

• KSM-66 — A full-spectrum ashwagandha root extract standardized to at least 5% withanolides. The most commonly studied extract in clinical trials. Typical dose: 300–600 mg/day.
• Sensoril — An extract from both roots and leaves, standardized to at least 10% withanolides. Tends to be more calming/sedating. Typical dose: 125–250 mg/day.

If you are new to ashwagandha, start at the lower end (300 mg/day) and assess your response over 2–4 weeks before increasing. Effects are typically cumulative — most people notice meaningful changes after 4–8 weeks of consistent use.

Cycling: Some practitioners recommend cycling ashwagandha (e.g., 8 weeks on, 2–4 weeks off) rather than using it indefinitely, though there is no firm consensus on this. Listen to your body and consult a healthcare provider for personalized guidance.

When is the best time to take it?

Ashwagandha can be taken in the morning or evening, depending on your goals:

• For stress management and performance: Morning dosing helps modulate cortisol throughout the day.
• For sleep support: Evening dosing, taken 1–2 hours before bed, leverages its calming properties. Sensoril, in particular, tends to be more sedating and is well-suited for nighttime use.
• Split dosing: Some people take 300 mg in the morning and 300 mg in the evening for around-the-clock support.

Take ashwagandha with food to improve absorption and reduce the chance of mild stomach upset. It does not need to be taken with fat specifically, but a meal helps.

What forms are available?

• Capsules — The most popular format, typically containing standardized extracts like KSM-66 or Sensoril. Convenient and precisely dosed.
• Powder — Raw ashwagandha root powder can be mixed into smoothies, warm milk, or "moon milk" recipes. The taste is earthy and slightly bitter. Note that raw powder is less concentrated than standardized extracts, so dosing must be adjusted accordingly.
• Gummies — Increasingly popular. Check that the gummy contains a clinically meaningful dose and a standardized extract, not just ashwagandha-flavored sugar.
• Liquid extract — Tinctures that can be added to water or taken under the tongue. Flexible dosing but may have a strong herbal taste.

For reliable results, choose a product that specifies its withanolide content (typically 5–10%) and uses a named extract (KSM-66 or Sensoril).

What are the side effects and precautions?

Ashwagandha is generally well tolerated, but it is not without considerations:

Common side effects:

• Mild drowsiness (more likely with Sensoril or higher doses)
• GI discomfort (nausea, diarrhea, stomach upset), usually resolved by taking with food
• Headache (uncommon)

Who should be cautious or avoid ashwagandha:

• Pregnant or breastfeeding women — Ashwagandha is traditionally contraindicated during pregnancy.
• People with autoimmune conditions (lupus, rheumatoid arthritis, Hashimoto's) — Ashwagandha can stimulate the immune system, which may worsen autoimmune symptoms.
• Hyperthyroidism or thyroid medication users — Ashwagandha can increase thyroid hormone levels, potentially causing interactions with thyroid medications like levothyroxine.
• People on sedatives or anti-anxiety medications — Ashwagandha may enhance sedative effects.
• Nightshade sensitivity — Ashwagandha belongs to the Solanaceae (nightshade) family. Individuals sensitive to nightshades may react.

Rare but reported: Some cases of liver injury have been associated with ashwagandha, though causation is debated and the incidence is very low. If you develop signs of liver issues (yellowing of skin/eyes, dark urine, severe fatigue), discontinue use and consult a doctor.

The Bottom Line

Ashwagandha is one of the most well-researched adaptogenic herbs, with meaningful evidence supporting its use for stress reduction, sleep improvement, physical performance, and cognitive function. A daily dose of 300–600 mg of a standardized extract like KSM-66 is a reasonable starting point for most adults.

Because ashwagandha works best with consistent daily use over weeks, tracking your intake and how you feel is incredibly valuable. Supplement Tracker helps you log ashwagandha alongside your other supplements, note subjective changes in stress and sleep, and maintain the daily consistency that adaptogenic herbs require to deliver results.