KSM-66 Ashwagandha for Sleep and Stress: The Trials

Does KSM-66 help sleep? In the best trial so far, 300mg twice daily for ten weeks shortened the time people with insomnia took to fall asleep (from about 42 to 29 minutes, against 42 to 34 on placebo) and raised sleep efficiency, measured by a wrist actigraph rather than self-report. On stress, the same dose cut morning cortisol by 27.9% from baseline over 60 days, against 7.9% on placebo. The effects are real but modest, the trials are small, and rare liver injury has been reported. Here is what each trial actually found, how to dose it, and who should not take it.

KSM-66 vs Sensoril: Different Extracts, Different Trials

This is the most important distinction in ashwagandha supplementation, and many review sites treat the two as interchangeable. KSM-66 is a root-only extract standardised to at least 5% withanolides, made by Ixoreal Biomed; the Chandrasekhar trial paper describes it as extracted "without using alcohol or any synthetic solvents". KSM-66 trials have reported lower cortisol (−27.9% from baseline versus −7.9% on placebo, Chandrasekhar 2012), lower anxiety scores on the DASS questionnaire (−75.6% from baseline in the same trial), and larger strength gains in young men who were resistance training (roughly one-and-a-half times the placebo group's gains, Wankhede 2015). A testosterone figure often attached to KSM-66 actually comes from a different extract: Lopresti et al. (2019) used Shoden and reported a 14.7% greater rise than placebo.

Sensoril is a root-and-leaf extract, made by Natreon, standardised to a higher withanolide-glycoside content. Its main stress trial (Auddy et al., 2008) tested 125mg once daily up to 250mg twice daily for 60 days in 98 stressed adults; as summarised in a later systematic review, serum cortisol fell by 14.5% to 30.5% from baseline depending on dose. It is often described as the more calming extract, but no trial has compared it head to head with KSM-66 for sleep, so treat that as a reasonable hypothesis rather than a finding.

For a broader view of how ashwagandha fits into nootropic protocols, see our comprehensive ashwagandha guide and our complete adaptogens overview.

What Does the Sleep Data Actually Show?

Langade and colleagues ran two separate sleep trials, and supplement marketing routinely merges them into one. The first (Cureus, 2019; 11(9):e5797) gave 300mg of root extract twice daily for 10 weeks to 60 participants — 40 on treatment, 20 on placebo, 58 analysed — and measured sleep by actigraphy. Sleep efficiency rose from 75.63% to 83.48% on treatment against 75.14% to 79.68% on placebo, and sleep onset latency fell from 41.6 to 29.0 minutes against 42.0 to 34.0 minutes. The second (Journal of Ethnopharmacology, 2021; 264:113276) ran 8 weeks in 80 participants — 40 healthy and 40 with diagnosed insomnia, not 80 healthy adults — and found sleep onset latency and sleep efficiency the most improved parameters (both p < 0.0001), with a larger effect in the insomnia arm than the healthy one.

Two cautions about how these trials are usually quoted. Neither paper states a percentage improvement in sleep quality, and neither reports a "non-restorative sleep subscore". The widely repeated 72% figure belongs to a different study on a different preparation — Deshpande et al. (2020, Sleep Medicine), 120mg of Shoden once daily for six weeks in 150 healthy adults — where 72% was the self-reported improvement against 29% on placebo. Both sample sizes are small, and the trials on each extract come from a small number of research groups, so independent replication is still thin.

Note also what was measured. The Langade trials used actigraphy — a wrist sensor that infers sleep from movement — plus questionnaires, not overnight polysomnography, so they tell you about time to fall asleep and time spent asleep rather than about deep or REM sleep.

Taken together, this evidence points to a realistic expectation: with consistent daily use of 600mg KSM-66 (300mg twice a day), some people fall asleep a little faster and sleep a little more efficiently after several weeks, most clearly in people who already have insomnia. It is not a sedative, and it will not fix sleep that is short because of late caffeine, screens or shift work. See our sleep optimization category and sleep supplements guide for the alternatives.

KSM-66 Dosage for Sleep and Stress

For stress and cortisol: 300mg KSM-66 twice daily, as in the Chandrasekhar and Salve trials; in Salve et al. (2019) that 600mg/day dose lowered cortisol about twice as much as 250mg/day. For sleep: the Langade trials also used 300mg twice daily. For Sensoril, the studied range runs from 125mg once daily to 250mg twice daily. The strength trial (Wankhede 2015) split its dose too — one capsule shortly after waking, one shortly before bed.

On timing: the trials split doses between morning and evening, and none compared morning-only with evening-only dosing. If you take one daily dose and your goal is sleep, the evening is the practical choice; drowsiness is a listed side effect for some people. How long does KSM-66 take to work? The sleep and cortisol results were measured at 8 to 10 weeks, so judge it after about two months of steady use, not after a few nights. Our KSM-66 dosage and timing guide covers the morning-versus-night choice in more detail.

Stacking Ashwagandha for Sleep

People often combine ashwagandha with magnesium glycinate and L-theanine in the evening, on the reasoning that each is thought to act on a different pathway. No trial has tested that combination, so if you try it, add one ingredient at a time so you can tell which one, if any, is helping — see our magnesium for sleep guide for how the magnesium piece fits in.

Avoid combining ashwagandha with prescription sedatives, anxiolytics or sleep medication without medical supervision: NCCIH lists sedatives among the medicines it may interact with.

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Who Should Avoid Ashwagandha

Ashwagandha is not for everyone. According to NCCIH, it should be avoided in pregnancy and not used while breastfeeding; it is not recommended before surgery or for people with autoimmune or thyroid disorders (in one trial, 600mg/day raised T3 and T4 in people with subclinical hypothyroidism); and it may interact with medicines for diabetes and high blood pressure, immunosuppressants, sedatives, anticonvulsants and thyroid hormone. People with hormone-sensitive prostate cancer should avoid it. Side effects some people report include drowsiness, stomach upset, diarrhoea and vomiting, and NCCIH notes that "although it is rare, there have been a number of cases that link liver injury to ashwagandha supplements" — stop and get medical advice if you notice yellowing skin or eyes, dark urine or unusual tiredness. If you take regular medication, ask your doctor or pharmacist before starting. More detail is in our ashwagandha side effects guide.

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Researched and drafted with AI assistance from published sources; edited and published by NorwegianSpark SA · Last updated: 30 September 2026

Disclaimer: This content is for informational purposes only and is not medical advice. Consult a healthcare professional before starting any supplement regimen.