Ashwagandha and stress: how it affects cortisol
Cortisol is the body's most important stress hormone – and the reason ashwagandha has attracted so much attention. Here we go through what the hormone does, what the studies actually show and where the limits of the supplement's effect lie.
What is cortisol and why does it matter?
Cortisol is produced in the adrenal glands and controlled by the brain's stress system, the HPA axis. The hormone is vital: it wakes you up in the morning, mobilises energy and sharpens focus in the face of acute danger. Without cortisol you would neither manage to get out of bed nor react quickly when it counts.
Levels normally follow a clear daily rhythm: a peak shortly after waking, then a slow decline towards night. It is when that curve flattens out – high all day, too high in the evening – that stress starts to show up in both sleep and mood.
The problem arises when levels stay high week after week. Chronically elevated cortisol is linked to sleep problems, difficulty concentrating, sugar cravings and increased abdominal fat. The body is built for short bursts of stress – not for constant alert.
What happens in the body under prolonged stress?
Under persistent stress, the system never gets the chance to return to rest mode. Sleep becomes shallower, which in turn raises stress levels the next day. A vicious circle, plain and simple.
It is precisely that circle that makes cortisol such an interesting target. Lower the stress response and sleep often improves – and with better sleep you can handle more stress the next day. Small changes can therefore have a bigger effect than they first appear to.
Signs that stress has gone too far include constant tiredness, irritability, heart palpitations and memory problems. If several of these sound familiar, read your national health service's advice on stress and consider contacting your doctor – before you start looking for solutions on the supplement shelf.
How ashwagandha affects cortisol according to the studies
Ashwagandha is the herb with the strongest clinical evidence in the area of stress. Three studies stand out:
| Study | Participants and dose | Result |
|---|---|---|
| Chandrasekhar 2012 | 64 chronically stressed adults, 600 mg KSM-66/day for 60 days | Cortisol −27.9 %, perceived stress −44 % versus placebo |
| Salve 2019 | 58 healthy adults, 250 or 600 mg/day for 8 weeks | Both doses lowered cortisol and stress; 600 mg most clearly |
| Lopresti 2019 | 60 adults with mild anxiety, 240 mg extract/day for 60 days | Lower anxiety scores and reduced morning cortisol |
The pattern is consistent: daily intake of a standardised root extract for at least eight weeks lowers both measured cortisol and the stress participants themselves report. The studies are relatively small, but the results point in the same direction study after study. For an overview of the herb's other effects, see our article on the effects of ashwagandha according to the research.
KSM-66 root extract with 500 mg per capsule – GMP-manufactured and third-party tested.
See current price »What is an adaptogen – and is ashwagandha one?
Adaptogens are herbs thought to help the body adapt to stress, rather than dampening or stimulating in a single direction. The concept is debated, and EFSA has not authorised any health claims for ashwagandha.
What sets ashwagandha apart from many other herbs, however, is the number of placebo-controlled studies. Researchers believe the withanolides in the root dampen the activity of the HPA axis, which would explain the lower cortisol readings. The mechanism is not fully mapped out, though.
How quickly will you notice an effect on stress?
Give it time. The studies measured their main outcomes after 60 days. Some participants noticed a difference after a couple of weeks, but the full effect builds up slowly.
Consistency beats timing: take the dose every day, morning or evening. Which time of day best suits your goal is something we sort out in our article on when to take ashwagandha.
Can you measure your cortisol?
Yes, cortisol can be measured in blood, saliva or urine, and private lab tests have become popular. But interpret the numbers with caution. Cortisol varies sharply over the day – highest in the morning, lowest around midnight – and is affected by everything from sleep to the previous day's workout.
A single reading therefore says rather little. In the studies, cortisol was measured at the same time of day, before and after, under controlled conditions. For you as an individual, your own experience is often a better measure: are you sleeping better, are you less easily irritated, do you have more energy?
If you suspect a genuine hormonal disorder, testing should be done through your doctor, not via a home test kit.
Ashwagandha is not the whole solution
No supplement compensates for a life in constant imbalance. The basics come first:
- Sleep: 7–9 hours, at the same times every day.
- Movement: regular physical activity measurably lowers stress levels.
- Boundaries: breaks during the working day and screen-free time before bed.
Ashwagandha can be a support on top of the basics – not instead of them. You will find more everyday tools in our range for stress and recovery, and our comparison of the best ashwagandha shows what separates the products.
When should you seek help instead?
Seek medical advice if stress is giving you sleepless nights week after week, feelings of panic, low mood, or if you no longer recover over weekends and holidays. These can be signs of burnout, and then your doctor is the right route – not supplements. The earlier you seek help, the shorter the road back usually is.
For healthy but stressed adults, the situation is simpler: a daily capsule of KSM-66 for eight weeks is a well-documented, low-risk experiment. Evaluate, and only keep what actually helps you.
Frequently asked questions
How much does ashwagandha lower cortisol?
In the most cited study, from 2012, cortisol levels fell by an average of 27.9 percent after 60 days on 600 mg of KSM-66 per day. Later studies have shown reductions in the same direction, though often smaller. The exact effect varies between individuals and depends on dose, stress level and how long you take the supplement.
How long does it take before stress decreases?
The studies measured their results after 30 to 60 days, and the clearest effects were seen at the end of the trials. Some participants reported improvement after as little as two to four weeks. Allow at least a month of daily intake before you evaluate, and ideally give it two months before drawing conclusions.
Can I take ashwagandha if I have burnout?
Burnout is a medical condition that requires proper care, time off and professional follow-up. Ashwagandha is a food supplement and replaces none of this. Talk to your doctor before adding supplements, so nothing clashes with your treatment. If you suspect burnout: contact your doctor or your national health service first.
What dose was used in the stress studies?
Most of the stress studies used 600 mg of standardised root extract per day, often split into two doses. A 2019 dose comparison tested 250 versus 600 mg and found that both lowered cortisol and perceived stress, but that the higher dose gave the clearest results. Below 240 mg per day, the evidence is weak.
Sources
- Chandrasekhar K et al. (2012). A prospective, randomized double-blind, placebo-controlled study of ashwagandha root extract in reducing stress and anxiety. Indian J Psychol Med.
- Salve J et al. (2019). Adaptogenic and anxiolytic effects of ashwagandha root extract in healthy adults. Cureus.
- Lopresti AL et al. (2019). An investigation into the stress-relieving and pharmacological actions of an ashwagandha extract. Medicine (Baltimore).
- Pratte MA et al. (2014). An alternative treatment for anxiety: a systematic review of human trial results for ashwagandha. J Altern Complement Med.
- 1177 Vårdguiden – on stress and when to seek medical care.
- EFSA – Botanicals: assessment of plant-based substances in food.