Start here if you came for the practical answer — dose, timing, how long it takes, side effects, vs melatonin: Ashwagandha for Sleep, the complete guide.
Two bottles sit on a shelf. Both say "Ashwagandha extract, standardized to 5% withanolides." Same herb, same percentage, similar price. One of them contains the plant material used in the clinical research you've probably heard about. The other doesn't.
The difference is one word — and most labels are in no hurry to print it.
Root is the part with the track record
Ashwagandha (Withania somnifera) has been used in Ayurvedic practice for well over two thousand years — and that tradition is built on the root. When researchers began testing ashwagandha in modern randomized, placebo-controlled trials — for stress and sleep quality — the overwhelming majority of that work used root extracts, typically at 250–600mg per day.
KSM-66® is root-only by design. It is the extract used in a 60-day trial in adults under chronic stress (PMID 23439798) and in a sleep trial in patients with a clinical sleep complaint (source: the evidence page). When someone cites "the ashwagandha research" on a podcast, this is often the material behind it.
So why do some products use leaf?
Three differences worth knowing:
- Leaves are cheaper. They grow back; harvesting roots means harvesting the whole plant. Leaf biomass costs less per kilo.
- Leaves are naturally higher in withanolides. So the same "5% withanolides" on a label can describe quite different material. The percentage tells you about a marker compound. It tells you nothing about whether the extract matches what was studied.
- Many labels don't say which. In our count of 336 labels, 27% didn't name the plant part.
To be clear: this isn't a safety scare. Leaf extract isn't poison. The point is narrower and more important — if the reason you're buying ashwagandha is the clinical research, then it matters whether your capsule contains what the clinical research actually tested. There is an ongoing debate inside the supplement industry about leaf versus root for exactly this reason, and the traditional pharmacopeia standard has centered on root.
How to read an ashwagandha label in 20 seconds
- Find the plant part. Does it say "root extract"? If the label just says "ashwagandha extract" or says "leaf" — you now know why.
- Look for a branded, studied extract. A name like KSM-66® means the extract carries its own published research file — you're not extrapolating from a different material.
- Check the dose against the research. Most positive trials used 250–600 mg of root extract per day. A "proprietary blend" that hides the ashwagandha dose inside a multi-gram mixture makes this check impossible.
- Ignore the withanolide percentage alone. It's a standardization marker, not a quality verdict — and leaf material reaches a given percentage more easily than root.
Where we stand
Small Hours uses KSM-66® ashwagandha — root-only, standardized to at least 5% withanolides — at 600 mg per night, the daily amount used in the two KSM-66 trials we cite (given there as 300 mg twice a day), printed plainly on the label. No blends to hide it in. It's there because KSM-66® supports a calmer stress response.†
Not because root is magic. Because if we're going to point at the research, we'd rather be holding the same thing the researchers were.
See the full Small Hours label →
This article is for educational purposes and is not medical advice. Talk to your healthcare provider before starting any supplement, especially if you take medication or manage a health condition.