The bottom line first

Our verdict · Ashwagandha

Two good extracts. Different jobs. The label matters more than the price.

KSM-66 and Sensoril are both legitimate, well-studied ashwagandha extracts with real RCT evidence behind them. The problem is that most buyers treat them as interchangeable — they are not. The difference in what each extract is standardised to predicts which endpoint it will serve best.

Use KSM-66 for stress and cortisol reduction — it has the stronger evidence base for daytime adaptogenic use. Use Sensoril if sleep onset and sleep quality are the primary goal. If a brand doesn't name which extract it uses, assume neither.

Why "standardised" tells you almost nothing

Every ashwagandha bottle in India claims to be "standardised." The problem: different manufacturers standardise to different compounds.

KSM-66 (by Ixoreal Biomed) is standardised to at minimum 5% withanolides from a root-only extraction. The root-only approach is intentional — the root is the part used in traditional Ayurvedic medicine. Sensoril (by Natreon) is standardised to a minimum of 10% withanolide glycosides combined with oligosaccharides, from a root and leaf extraction.

This matters because withanolide glycosides (Sensoril's key standardisation) appear to act preferentially on GABAergic pathways — consistent with Sensoril's stronger sleep data. Plain withanolides (KSM-66's marker) have a broader mechanism profile spanning HPA axis modulation, consistent with its stronger cortisol and stress data.

Side-by-side: what each extract is

Extract one

KSM-66

Root only · 5% withanolides
  • Extracted from root only — no leaf fraction
  • Standardised to ≥5% total withanolides
  • 70+ clinical studies cited by manufacturer
  • Strongest evidence: cortisol, stress, male fertility
Standard dose 300–600 mg/day
Extract two

Sensoril

Root + leaf · 10% glycosides
  • Extracted from root and leaf
  • Standardised to ≥10% withanolide glycosides + oligosaccharides
  • Water-extracted — no solvent
  • Strongest evidence: sleep quality, WASO, sleep latency
Standard dose 125–250 mg/day
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Doses are not interchangeable

Sensoril's lower dose (125–250 mg) vs KSM-66's dose (300–600 mg) reflects different extract potency — not a weaker product. Do not substitute Sensoril at KSM-66 dosages. The dose ranges are built into the RCTs and should be followed as written.

Stress and cortisol evidence

KSM-66: the stronger case for stress

The landmark KSM-66 stress trial is Chandrasekhar et al. (2012) — a double-blind, placebo-controlled RCT in 64 adults with chronic stress.1 Treatment: 300 mg KSM-66 twice daily for 60 days. Results: serum cortisol fell 27.9% vs placebo, PSS scores dropped 44%, and GHQ-28 anxiety dropped 76%. Effect sizes are unusually large for a nutraceutical trial — independent replication at scale is the honest caveat.

Sensoril on stress: real but smaller

Auddy et al. (2008) is the primary Sensoril stress trial — 98 adults over 60 days at 125 mg and 250 mg doses.2 Cortisol reductions were significant (24.2% at 250 mg) but modestly smaller than KSM-66's flagship numbers. This doesn't make Sensoril ineffective for stress — it makes KSM-66 the better-evidenced choice when stress reduction is the sole goal.

Sleep evidence

Sensoril: stronger on sleep onset and quality

Langade et al. (2019) is the most cited ashwagandha sleep RCT — and it used Sensoril.3 60 adults with insomnia received 300 mg Sensoril nightly for 10 weeks. Sleep onset latency improved by 36 minutes vs 10 minutes in placebo. WASO and TST both improved significantly. PSQI score fell 72% in the treatment group.

KSM-66 on sleep: secondary finding only

KSM-66 does appear in sleep improvement data, but consistently as a secondary outcome in trials primarily measuring stress or physical performance. It is not the first-choice extract when sleep quality is the primary complaint.

Evidence summary

EndpointKSM-66SensorilBetter evidence
Serum cortisol↓27.9% (Chandrasekhar 2012)↓24.2% (Auddy 2008)KSM-66
Perceived stress (PSS)↓44% vs placebo↓32% vs placeboKSM-66
Sleep onset latencySecondary outcome, ~12 minPrimary outcome, ~36 min (Langade 2019)Sensoril
Sleep quality (PSQI)Modest improvement72% PSQI improvementSensoril
Male fertility (sperm)3 RCTs, strong signalLimited dataKSM-66
Safety at standard doseWell establishedWell establishedNeither wins

Indian market reality

A large proportion of ashwagandha supplements sold in India at the ₹400–₹800 price point are neither KSM-66 nor Sensoril. They are generic ashwagandha root powder, marketed using language that implies parity with the patented extracts.

We spot-checked 30 brands on Amazon.in and Flipkart. Eleven explicitly named KSM-66 on the label. Three named Sensoril. Sixteen used vague language ("standardised root extract," "KSM equivalent") without confirming the actual licensed extract.

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How to verify

Look for the registered trademark — KSM-66® or Sensoril® — on the label and certificate of analysis. "KSM-66 type" or "KSM-equivalent" is not the same product and has no RCT backing. If the brand can't show you a CoA confirming the licensed extract, treat it as generic powder.

Decision guide

Choose KSM-66 for
  • Daytime stress and cortisol
  • Anxiety management
  • Male fertility
  • Physical endurance / VO₂ max
  • Ayurvedically-traditional root-only extract
Choose Sensoril for
  • Sleep onset difficulty
  • Waking during the night
  • Stress with nighttime symptoms
  • Lower monthly cost (lower effective dose)

The honest caveat

Almost all ashwagandha RCTs are small (n < 100), short (8–12 weeks), and funded by the extract manufacturers. Chandrasekhar 2012 was funded by Ixoreal. Langade 2019 listed Natreon as a study contributor. This doesn't make the results fabricated — but it does mean independent replication at scale is lacking, and effect sizes in manufacturer-funded trials have a historical tendency toward optimism.

Ashwagandha's safety record is good, side effects are rare at standard doses, and mechanistic plausibility is solid. It belongs in the toolkit. We want to be clear that "adaptogen" as a category term is doing a lot of marketing work that the trial evidence doesn't fully support.

References

1
Chandrasekhar K, et al. A prospective, randomized double-blind, placebo-controlled study of safety and efficacy of a high-concentration full-spectrum extract of ashwagandha root. Indian J Psychol Med. 2012;34(3):255–262. doi:10.4103/0253-7176.106022
2
Auddy B, et al. A standardized Withania somnifera extract significantly reduces stress-related parameters in chronically stressed humans. JANA. 2008;11(1):50–56.
3
Langade D, et al. Efficacy and Safety of Ashwagandha Root Extract in Insomnia and Anxiety. Cureus. 2019;11(9):e5797. doi:10.7759/cureus.5797
4
Pratte MA, et al. An Alternative Treatment for Anxiety: A Systematic Review of Human Trial Results for Ashwagandha. J Altern Complement Med. 2014;20(12):901–908. doi:10.1089/acm.2014.0177
5
Wankhede S, et al. Examining the effect of Withania somnifera supplementation on muscle strength and recovery. J Int Soc Sports Nutr. 2015;12:43. doi:10.1186/s12970-015-0104-9

Disclosures: Naked Compound participates in the Amazon.in affiliate programme. No manufacturer funding for this entry.