Clinical trial evidence on ashwagandha dosing for stress, sleep, energy, and exercise performance. Covers KSM-66 vs Sensoril, timing, cycling, and safety.
Ashwagandha (Withania somnifera) is one of the most researched adaptogens, with over 20 randomised controlled trials published in the last decade. But the clinical literature reveals something important: the dose, the extract type, and the timing all significantly affect what benefits you get.
A 300 mg dose of KSM-66 twice daily produced a 27.9% reduction in serum cortisol in one landmark trial. But a different trial using 600 mg of generic root powder showed minimal effects. The extract matters as much as the milligrams.
This guide breaks down the evidence-based dosing for each major use case, compares the two most studied extracts (KSM-66 and Sensoril), and covers the practical questions: when to take it, whether to cycle, and who should avoid it.
For stress and anxiety (strongest evidence)
Most clinical trials used 300 mg twice daily (600 mg/day total) of a standardised root extract, typically KSM-66. The key study by Chandrasekhar et al. (2012) found that this dose reduced perceived stress scores by 44% and cortisol levels by 27.9% over 60 days compared to placebo.
A lower dose of 240 mg/day of Sensoril (a root + leaf extract) also showed statistically significant reductions in anxiety scores on the Hamilton Anxiety Scale in a 2019 study by Lopresti et al.
Recommended range for stress: 300-600 mg/day of KSM-66, or 240-480 mg/day of Sensoril.
For sleep quality
Ashwagandha is not a sedative, but it can improve sleep indirectly by lowering cortisol. A 2020 study in Cureus found that 600 mg/day of ashwagandha root extract for 8 weeks improved sleep quality scores by 72% compared to 29% in the placebo group (measured by Pittsburgh Sleep Quality Index). A 2019 trial using just 300 mg of KSM-66 twice daily also found significant improvements in sleep onset latency and overall sleep quality.
Recommended range for sleep: 300-600 mg/day, taken in the evening.
For energy and physical performance
Several trials have examined ashwagandha for exercise performance. A 2015 study in the Journal of the International Society of Sports Nutrition found that 300 mg of KSM-66 twice daily for 8 weeks increased VO2 max by 4.91 mL/kg/min (vs 1.42 for placebo) and improved upper and lower body strength significantly.
A 2021 systematic review in Nutrients pooling 12 studies concluded that ashwagandha supplementation at 120-1,250 mg/day for 2-12 weeks improved physical performance markers, with 600 mg/day being the most common effective dose.
Recommended range for performance: 300-600 mg/day of KSM-66.
For thyroid support
A small 2018 study in Journal of Alternative and Complementary Medicine found that 600 mg/day of ashwagandha root extract normalised thyroid indices (TSH, T3, T4) in subclinical hypothyroid patients over 8 weeks. However, this is a single study with a small sample (50 participants), and ashwagandha should be used cautiously with thyroid conditions.
Not recommended for self-treatment. If you have a thyroid condition, talk to your doctor before supplementing.
These are the two most clinically studied ashwagandha extracts, and they are not interchangeable.
KSM-66 is a full-spectrum root extract standardised to at least 5% withanolides. It is produced using a proprietary extraction process that uses no alcohol or chemical solvents. KSM-66 has the most published clinical trials of any ashwagandha extract — over 24 gold-standard studies covering stress, sleep, energy, sexual health, and cognitive function.
Sensoril is a root and leaf extract standardised to at least 10% withanolides. The higher withanolide concentration means effective doses are typically lower (240-480 mg vs 300-600 mg for KSM-66). Sensoril tends to have more pronounced calming effects and is often preferred for anxiety and sleep.
Practical differences:
What about generic ashwagandha? Many cheap products use unstandardised root powder. Without withanolide standardisation, you have no guarantee of active compound content. The clinical evidence specifically supports standardised extracts. If the label does not specify KSM-66, Sensoril, or a withanolide percentage, be cautious.
With food — Always. Ashwagandha is fat-soluble and absorbs better with a meal. Taking it on an empty stomach can cause mild nausea in some people.
Morning vs evening depends on your goal:
How long before it works: Do not expect overnight results. Most clinical trials ran for 8-12 weeks, with measurable changes in cortisol and stress scores appearing around weeks 4-6. Give it a minimum of 4 weeks before evaluating whether it works for you.
The clinical trials ran continuously for 8-12 weeks without cycling, and no safety concerns emerged. However, there are no long-term studies (12+ months) of continuous use.
Common cycling protocols (based on practitioner recommendations, not clinical data):
The practical answer: If you are using ashwagandha for a specific stressor (exams, a difficult work period), use it for the duration needed and then stop. If you are using it ongoing for generalised stress management, a cycle of 2-3 months on with a 2-4 week break is a reasonable precaution until longer-term data is available.
Cycling also helps you assess whether you still need it. After a break, if your stress symptoms return, that confirms it was providing benefit.
Ashwagandha is generally well-tolerated at standard doses. The most commonly reported side effects in clinical trials are mild and include:
Who should NOT take ashwagandha:
Drug interactions to watch:
When buying ashwagandha in Australia, check for:
1. Extract type — Look for KSM-66 or Sensoril on the label. These are trademarked and guaranteeing standardised withanolide content.
2. Withanolide percentage — At minimum 5% for KSM-66, 10% for Sensoril. If no percentage is listed, the product may be unstandardised root powder.
3. Dose per capsule — Many Australian products contain 500-600 mg per capsule of KSM-66, designed for once-daily dosing. Others contain 300 mg, intended for twice-daily use. Either approach is supported by clinical data.
4. Other ingredients — Some products add black pepper extract (BioPerine) to improve absorption. This is a reasonable addition but not essential.
5. TGA listing — In Australia, supplements should have an AUST L number on the label, indicating they are listed with the Therapeutic Goods Administration.
Price range in Australia: KSM-66 ashwagandha typically costs $0.30-$0.80 per serve from Australian retailers. Sensoril products are less common in the AU market but available via iHerb. Generic (unstandardised) products can be cheaper but lack quality guarantees.
You can compare current ashwagandha prices across Australian retailers on our [ashwagandha supplement page](/supplements/ashwagandha).
We break down clinical studies into actionable stress-anxiety advice — new articles, dosage updates, and Australian price drops. No spam, unsubscribe anytime.
Get personalised, evidence-based supplement recommendations in seconds.
Take the QuizThis article is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional before starting any supplement regimen.