Supplements
Ashwagandha for Stress and Sleep: What the Trials Actually Show
There is real research here, and it is more modest than the marketing. Here are the doses that were studied, who actually benefited, and the liver and thyroid risks worth knowing first.
Ashwagandha is having a long moment. It shows up in bedtime gummies, cortisol supplements, and every second video about stress. The pitch is always the same: an ancient herb that calms your nervous system and helps you sleep.
Here is the useful part. There actually is a stack of randomized trials behind it, which is more than most trending supplements can say. There are also some real problems with that research, and two safety issues worth knowing about before you buy a bottle.
What the trials found
Start with the strongest signal, which is anxiety and stress.
A systematic review and meta-analysis pooled 12 randomized trials covering 1,002 adults between 25 and 48 years old. Ashwagandha significantly reduced both anxiety and stress scores compared with placebo, with the benefit for stress showing up at doses of about 300 to 600 mg a day (Akhgarjand, 2022).
A second meta-analysis of 9 trials in 558 people put numbers on it that are easier to picture. Perceived Stress Scale scores dropped by about 4.7 points, Hamilton Anxiety scores by about 2.2 points, and serum cortisol fell too (Arumugam, 2024).
That cortisol finding is the reason ashwagandha ended up at the center of the cortisol conversation online. It is a real measured change, not a marketing invention.
The sleep evidence is smaller but real
A meta-analysis of 5 randomized trials in 400 adults found a small but significant improvement in sleep. The benefit was clearer in three specific situations: people actually diagnosed with insomnia, doses of 600 mg a day or more, and treatment lasting 8 weeks or longer (Cheah, 2021).
That last point matters. This is not a supplement that does much on night one. The trials that worked ran for two months.
One of the better individual trials randomized 80 people, half healthy and half with insomnia, to ashwagandha root extract or placebo for 8 weeks. Both groups improved, but the people with insomnia improved more, particularly in how long it took them to fall asleep and how much of their time in bed was actually spent asleep (Langade, 2020).
Read that carefully, because it is the pattern across this whole literature. If your sleep is already decent, there is not much for the herb to fix.
Where the research is weaker than it looks
Now the part the supplement ads leave out.
The most recent and most careful review of ashwagandha in people with diagnosed mental health conditions pulled together 14 trials, 360 people treated and 353 controls. It found real improvements in anxiety, depression, stress, and sleep quality. But the authors flagged the same limitations you see everywhere in this field: a small number of studies, substantial disagreement between them, and outlier results pulling the average around. When they reanalyzed the data with a more conservative statistical model, the anxiety finding held up and the depression finding did not (Marchi, 2025).
The earlier meta-analysis rated the overall certainty of its own evidence as low (Akhgarjand, 2022). That is the researchers themselves telling you not to over-read their result.
Two other things are worth noticing. Most of these trials ran 8 weeks, so nobody really knows what a year of daily use does. And a lot of the studies were funded or run by people with a commercial interest in the extract, which is the norm in supplement research and a reason to keep expectations moderate.
The two safety issues
Your liver. A published case series describes five people who developed liver injury after taking ashwagandha supplements, collected in Iceland and through the US Drug-Induced Liver Injury Network. All five developed jaundice, along with nausea, itching, and fatigue, starting somewhere between 2 and 12 weeks after they began taking it. Nobody went into liver failure, and liver tests returned to normal within 1 to 5 months in the four patients who were followed (Björnsson, 2020).
Five cases against millions of users is a rare event, not a reason to panic. It is a reason to stop and get checked if you start feeling unusually tired, itchy, or nauseated, or if your skin or eyes look yellow.
Your thyroid. A case report describes a 32-year-old woman who developed thyrotoxicosis, meaning too much thyroid hormone in her system, while taking ashwagandha capsules for fatigue. She had no symptoms while taking it occasionally, but developed them after raising her dose. Everything resolved once she stopped (van der Hooft, 2005).
This one is especially relevant for women, since thyroid conditions are far more common in us. If you have a thyroid diagnosis or take thyroid medication, this is a conversation to have with your doctor before you start, not after.
Who should skip it entirely
Do not take ashwagandha if you are pregnant or trying to become pregnant. Traditional use includes inducing miscarriage, and there is no safety data supporting use in pregnancy.
Be cautious and talk to your doctor first if you have a thyroid condition, an autoimmune condition, any liver problem, or if you take sedatives, thyroid medication, immunosuppressants, or blood sugar or blood pressure medication.
If you decide to try it
The doses that were actually studied are 300 to 600 mg a day of a standardized root extract, taken for at least 8 weeks before you judge it. Higher is not better here, and the trials that used more did not do better.
Buy from a brand that publishes third-party testing, since supplement quality varies enormously and you are relying entirely on the label. Take it consistently rather than only on bad days. And give it a genuine trial period, then stop and see whether anything changes. That is the only real way to know whether it is doing something for you.
The honest summary
Ashwagandha is one of the better-supported supplements in the stress and sleep category, which is a lower bar than it sounds like. The anxiety evidence is the most consistent. The sleep evidence works mainly for people who are actually sleeping badly, at 600 mg, over about two months.
It is not a replacement for the things that move stress and sleep the most, which remain unglamorous: consistent sleep and wake times, morning daylight, movement, and dealing with whatever is actually keeping you up. Ashwagandha at its best is a modest assist on top of those, and it comes with two rare but genuine risks that most bottles do not mention.
References
- Akhgarjand C, et al. Does Ashwagandha supplementation have a beneficial effect on the management of anxiety and stress? A systematic review and meta-analysis of randomized controlled trials. Phytotherapy Research. 2022. PMID: 36017529
- Arumugam V, et al. Effects of Ashwagandha (Withania somnifera) on stress and anxiety: a systematic review and meta-analysis. Explore. 2024. PMID: 39348746
- Cheah KL, et al. Effect of Ashwagandha (Withania somnifera) extract on sleep: a systematic review and meta-analysis. PLOS ONE. 2021. PMID: 34559859
- Langade D, et al. Clinical evaluation of the pharmacological impact of ashwagandha root extract on sleep in healthy volunteers and insomnia patients: a double-blind, randomized, parallel-group, placebo-controlled study. Journal of Ethnopharmacology. 2020. PMID: 32818573
- Marchi M, et al. The effect of Withania somnifera (Ashwagandha) on mental health symptoms in individuals with mental disorders: systematic review and meta-analysis. BJPsych Open. 2025. PMID: 41140145
- Björnsson HK, et al. Ashwagandha-induced liver injury: a case series from Iceland and the US Drug-Induced Liver Injury Network. Liver International. 2020. PMID: 31991029
- van der Hooft CS, et al. Thyrotoxicosis following the use of ashwagandha. Nederlands Tijdschrift voor Geneeskunde. 2005. PMID: 16355578
Common questions
Does ashwagandha actually reduce stress?
The evidence for this is the strongest part of the research. A meta-analysis of 12 randomized trials in 1,002 adults found significant reductions in both anxiety and stress compared with placebo, with the stress benefit appearing at 300 to 600 mg a day. A second meta-analysis of 9 trials in 558 people found Perceived Stress Scale scores dropped by about 4.7 points and serum cortisol fell as well. The important caveat is that the researchers themselves rated the overall certainty of this evidence as low, because the trials are small and disagree with each other quite a bit.
How long does ashwagandha take to work for sleep?
Longer than most people expect. A meta-analysis of 5 trials in 400 adults found the benefit for sleep was clearest at doses of 600 mg a day or more and with treatment lasting at least 8 weeks. This is not a supplement that does much on the first night. If you try it, give it a genuine two-month run before deciding whether it helps, and understand that the effect was strongest in people actually diagnosed with insomnia rather than people who already sleep reasonably well.
Is ashwagandha safe to take every day?
For most people in the trials it was well tolerated, but there are two documented risks. A case series described five people who developed liver injury with jaundice starting 2 to 12 weeks after starting an ashwagandha supplement. All recovered within 1 to 5 months. Separately, a case report describes a woman who developed thyrotoxicosis, meaning too much thyroid hormone, while taking ashwagandha capsules, which resolved when she stopped. Both are rare. Stop and see a doctor if you develop jaundice, unusual itching, or persistent nausea and fatigue.
Who should not take ashwagandha?
Do not take it if you are pregnant or trying to conceive, since traditional use includes inducing miscarriage and there is no safety data for pregnancy. Talk to your doctor first if you have a thyroid condition or take thyroid medication, since ashwagandha can raise thyroid hormone levels, and thyroid conditions are much more common in women. The same goes for autoimmune conditions, any liver problem, and if you take sedatives, immunosuppressants, or medication for blood sugar or blood pressure.
