How to Reduce Cortisol: Can a Root Tame It?How to reduce cortisol: sleep, exercise, meditation, time outdoors, caffeine timing and ashwagandha, graded by evidence.

Deadline at 6. Stuck in traffic at 5:45. Seventeen unread WhatsApp groups. Your heart is racing, your jaw is clenched, and it's only Tuesday.

That feeling has a name, and it isn't "Tuesday". It's cortisol.

So, how to reduce cortisol? Spend five minutes on wellness Instagram and you'll get one answer: an old Indian root called ashwagandha. Some call it a miracle. Some call it a fad. Truth be told, it's neither. It has genuinely interesting trial data, but it isn't the first thing to reach for. Sleep, movement, meditation, time outdoors and caffeine timing have broader evidence, and they cost nothing. Below, each is graded by its human studies, the root included. (Ashwagandha is also in our night drink, SILT Nights, so we've read those trials more closely than most.)

So let's dig in. (Pun fully intended.)

What is cortisol? Your in-house alarm

Cortisol is your main stress hormone, made by your adrenal glands, the small glands that sit on top of your kidneys. Your brain (specifically the hypothalamus and pituitary gland) decides how much gets made¹. It helps regulate how your body uses sugar for energy, keeps blood pressure in check, damps down inflammation and helps run your sleep-wake cycle. Levels normally peak in the morning just before you wake up (part of what gets you out of bed) and are lowest in the evening, when you go to sleep¹.

Here's the thing: cortisol is not the villain. It's an alarm clock and a fire alarm rolled into one. The trouble? Modern life keeps pulling the fire alarm. Your body can't tell a tiger from a passive-aggressive email; it just reacts. So the goal isn't zero cortisol. It's a healthy rhythm: high when you need to get going, low when you need to switch off. The habits below help that evening dip happen.

Cortisol that stays very high for a long time is different: that's usually a sign of Cushing's syndrome, which needs a doctor¹.

"Stressed" is the feeling. Cortisol is the chemistry underneath it.

How to reduce cortisol: six ways, graded

The short answer on how to reduce cortisol: protect your sleep, move regularly, practise meditation or yoga, get outside and keep caffeine early. Ashwagandha comes last, as a supplement with some real cortisol trials behind it.

"Grade" is our editorial read of the studies cited below, not a clinical rating. Most are small, and many studied people who were ill or under particular stress.

Sleep and cortisol: protect the seven hours

Sleep is the cheapest cortisol lever there is, and a short night pushes the next evening's cortisol up. Adults aged 18 to 60 need seven or more hours a night, says the US Centers for Disease Control and Prevention².

In a lab study, healthy young men slept 11 pm to 7 am, only 4 am to 8 am, or not at all. After the short night, their cortisol between 6 pm and 11 pm the next evening was 37% higher than the evening before; after no sleep, 45% higher. The evening wind-down also started at least an hour late³. Short, yes, but it shows the mechanism: lose sleep, and your stress system takes longer to settle the next evening.

What helps is boring: a fixed wake-up time, a dark room and the phone out of arm's reach. For the bedtime ingredients people ask us about, we've looked at what glycine does for sleep.

Exercise and cortisol: move most days, not always flat out

Regular exercise programmes lowered cortisol over weeks in trials, even though a hard session raises it for a while. Both are normal.

Over weeks. A 2022 meta-analysis of 10 studies found that physical activity programmes lowered cortisol (moderate-certainty evidence) and improved sleep quality (low certainty). The catch: most participants were women with breast cancer, with few men and no older adults, so the authors warn against generalising⁴.

In the moment. In 12 trained men, 30 minutes at 60% and 80% of their maximal oxygen uptake raised cortisol by about 40% and 83% straight after. At 40%, an easy pace, it didn't rise significantly, and once the researchers corrected for fluid shifts and time of day, it actually fell⁵.

Our read (not a trial finding): keep your hard sessions, but on a high-stress day an easy walk, cycle or swim is more likely to leave cortisol lower. An all-out workout at 9 pm after a draining day is many things. A relaxation technique isn't one of them.

Meditation and cortisol: sit, breathe, stretch

Meditation and yoga lowered cortisol in large sets of randomised trials, even against active comparison groups. The effect is real but uneven: clearest in people with a physical illness.

• Meditation. A meta-analysis of 45 randomised trials compared meditation with an active control. Taken together, meditation lowered cortisol, blood pressure and heart rate; focused-attention styles, such as following your breath, lowered cortisol on their own⁶.
• Who benefits most. A second meta-analysis split the trials. In the 10 that measured cortisol in blood, meditation had a medium effect, but only in at-risk groups, mainly patients with a physical illness. In the 21 that used saliva, the effect was small and not significant, with a borderline effect in people living through stressful situations⁷.
• Yoga. Across 42 randomised trials against active controls, practices that included yoga postures were linked with lower evening and waking cortisol, lower resting heart rate and lower ambulatory blood pressure, though the programmes varied a lot⁸.

How to start: ten minutes of breath-focused meditation, or a beginner yoga class, at the same time daily. Consistency beats the app or the style.

Does time outdoors lower cortisol? Twenty green minutes

Probably, a little: time in a park, garden or any green patch seems to speed up cortisol's normal daily fall. You don't need a forest.

For eight weeks, 36 city dwellers spent 10 minutes or more somewhere that felt like nature, at least three times a week, whenever it suited them. During those outings, salivary cortisol fell 21.3% an hour faster than its usual daily decline. The best return per minute came at 20 to 30 minutes; benefits kept building after that, but more slowly. Sitting or walking made no difference to the cortisol drop⁹.

One study, no separate control group: promising, not settled. But a 20-minute walk in the colony park costs nothing, and doubles as easy movement.

Caffeine and cortisol: keep the coffee early

Caffeine raises cortisol, and daily coffee drinkers only partly adapt. Late caffeine also costs sleep, which takes you back to the first lever.

• Cortisol. In a crossover trial of 96 healthy men and women, caffeine raised cortisol across the day after five days without it. After five days on 300 mg or 600 mg a day, the 9 am dose no longer raised cortisol, but a second dose at 1 pm still did, until levels came back down in the evening¹⁰.
• Sleep. A meta-analysis of 24 studies found caffeine cut total sleep by 45 minutes, and worked out that a coffee (107 mg per 250 ml) should be had at least 8.8 hours before bed to avoid losing sleep¹¹. In another trial, 400 mg taken even six hours before bed disturbed sleep compared with a placebo¹².

For an 11 pm bedtime, that puts the last coffee at about 2 pm. If the 4 pm chai-and-biscuit break is sacred, keep the biscuit and swap the chai for a herbal tea.

Can a supplement help? Ashwagandha, graded

Possibly, a little. In short trials of stressed adults, ashwagandha root extract lowered blood cortisol more than a placebo. The trials are small, and feeling less stressed is a less consistent result: promising, not proven.

Meet the root (and the name)

Ashwagandha (Withania somnifera), also known as Indian winter cherry or Indian ginseng, is a woody shrub from the nightshade family whose root is an Ayurvedic rasayana, a herb meant to rejuvenate the body¹³. In Sanskrit, ashva means horse and gandha means smell, a nod to the root's very earthy aroma. (Folklore adds that it gives you the strength of a horse. We make no promises there.)¹⁴ And somnifera is Latin for "sleep-bringing"¹⁵. Clearly, people had opinions about this plant long before we had lab tests.

It's usually called an adaptogen, a herb thought to help the body adapt to stress¹³. That's a traditional idea, not a medical category. The compounds scientists measure most are withanolides, more than 70 of them in the root and leaf¹³. This section sticks to ashwagandha for stress; for everything else, see our guide to ashwagandha benefits.

Study 01 · The one everyone quotes

In a 2012 trial in the Indian Journal of Psychological Medicine, 64 adults aged 18 to 54 with chronic stress took either 300 mg of KSM-66 ashwagandha root extract twice a day (600 mg a day) or a placebo, for 60 days; 61 finished. Side effects, such as a blocked nose, constipation and drowsiness, were mild and turned up about as often on placebo: six reports versus five¹⁴. The headline numbers:

Study 02 · Does the dose matter?

A 2019 trial in Cureus gave 60 healthy but stressed adults, aged 18 to 55, either 250 mg or 600 mg a day of KSM-66 root extract, or a placebo, for eight weeks; 58 finished. Both doses beat placebo on stress scores and blood cortisol, and the bigger dose did more: by our maths from the paper's average readings, cortisol fell about 33% on 600 mg, about 17% on 250 mg and about 4% on placebo¹⁶. Worth knowing: the extract's maker supplied it for this trial¹⁶, as it did for the 2012 one¹⁴. Both are small, single-site trials of one branded extract.

What the newer reviews say

One or two trials can be a fluke, so researchers pool them. A 2022 meta-analysis of 12 trials with 1,002 adults found lower stress and anxiety scores than on placebo, but rated the certainty of that evidence as low¹⁷. A 2024 meta-analysis of nine trials (558 people) found lower blood cortisol too¹⁸. A 2023 review of nine studies lasting 30 to 112 days found cortisol fell, but none checked adrenal function or long-term effects, so its authors advise medical supervision¹⁹.

The newest reviews add a twist. A 2025 meta-analysis (488 people) found cortisol fell by about 1.2 µg/dL, but perceived stress didn't change significantly²⁰. A 2026 meta-analysis of 23 hormone trials (1,706 people) found lower cortisol, with wide variation between studies, and a small rise in the thyroid hormone T4²¹. NCCIH, part of the US National Institutes of Health, says some preparations may help with stress but calls the anxiety evidence unclear²², so read "ashwagandha for stress and anxiety" claims with care.

Not all ashwagandha is the same extract

"Ashwagandha" on a pack tells you very little. It could be root powder (churna), a root or leaf extract, or a blend, and without a withanolide percentage you can't tell how strong it is. Think of it like tea: "tea" can mean a sad dusty teabag or a single-estate Darjeeling. Same plant, very different cup.

Both trials above used one standardised root extract, KSM-66, from Ixoreal Biomed. The 2012 paper describes it as root-only, full-spectrum, standardised to at least 5% withanolides by lab testing (HPLC) and extracted without alcohol or synthetic solvents¹⁴. So the "27.9% lower cortisol" figure belongs to this extract, in stressed adults, over 60 days. It doesn't automatically carry over to a powder with a pinch of ashwagandha somewhere on the ingredient list.

The fine print: who should check first

Ashwagandha may be safe for short-term use, up to about three months, but there isn't enough information yet to judge long-term safety. Here's what NCCIH flags²²:

• Side effects: drowsiness, stomach upset, diarrhoea and vomiting in some people.
• Thyroid and autoimmune conditions: it isn't recommended if you have a thyroid or autoimmune disorder, or if you're about to have surgery.
• Pregnancy and breastfeeding: avoid it. People with hormone-sensitive prostate cancer should avoid it too.
• Medicines: it may interact with medicines for diabetes and blood pressure, thyroid hormone, sedatives, anti-seizure medicines and immunosuppressants.

Liver injury is rare, but documented. An Indian multi-centre series found 23 people with ashwagandha-linked liver injury between 2019 and 2022 and described 8 who had taken single-ingredient products. Five of the eight already had chronic liver disease; three of those developed acute-on-chronic liver failure and died²³. In five cases from Iceland and the US, jaundice appeared 2 to 12 weeks after starting; the four followed up recovered within one to five months²⁴.

Some regulators are stricter. Denmark's food authority says it is illegal to sell products containing ashwagandha there, citing a Technical University of Denmark risk assessment that flagged effects on sex hormones and reproduction²⁵. For the longer list, see our guide to ashwagandha side effects and who should avoid it.

And the big one: ashwagandha is not a replacement for medical care. If stress or anxiety is taking over your life, talk to a doctor or therapist.

When is it medical? Steroids and your doctor

Everyday stress and medical cortisol excess are different things. Cushing's syndrome is the medical version: too much cortisol for a long time, most often from taking high doses of steroid medicine such as prednisolone, and less often from a small non-cancerous growth in the pituitary or adrenal glands²⁶.

Its signs, such as a red, round face, more fat on the tummy and upper back with thinner arms and legs, and muscle weakness, usually come on gradually. See a doctor if you notice them, especially if you take steroid medicine²⁶, but don't stop steroids without talking to your doctor first²⁷.

A puffy face or a bit of belly fat on its own is not a diagnosis, whatever the reels say; our guide to high cortisol symptoms covers the real warning signs. None of the habits or supplements here treats Cushing's syndrome.

Where SILT lands

SILT Nights is a wind-down drink for the last hour before bed, built around the first lever on this list: a calmer run-up to sleep. It isn't a cortisol fix or a medicine, and it doesn't replace any of the habits above. When we put it together, a named, studied extract wasn't a "nice to have". It was the brief.

Each stick of SILT Nights has 300 mg of KSM-66 Ashwagandha root extract, alongside 3 g of glycine, 1.8 g of magnesium bisglycinate (250 mg elemental magnesium) and 200 mg of L-theanine, with no melatonin and no caffeine. The trials above tell you this extract has been studied on its own; they aren't a promise that any drink, ours included, will reproduce their numbers.

Every dose is printed on the label, with no proprietary blends, and there's a certificate of analysis for every ingredient on our science page (the KSM-66 one reads 5.3% withanolides against a 5% minimum). SILT is for everyday energy, gut and sleep. It doesn't treat medical conditions. For those, or if you're pregnant or on medication, talk to your doctor; the same goes if you have a liver or thyroid condition.

A helper, not a hero

Reducing cortisol comes down to the unglamorous basics above. Ashwagandha is a support act, not the headliner. We love a good root, but let's be real: no capsule, gummy or drink can out-supplement a life running on four hours of sleep and six coffees. (Curious about other calm-adjacent ingredients? We've looked at L-theanine for calm by night and focus by day.)

Think of ashwagandha as the calm friend in the group chat. Really helpful to have around, but they can't do all the work.

References

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2. Centers for Disease Control and Prevention. About Sleep. cdc.gov/sleep/about/index.html
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This article is for general information only and isn't medical advice. Please consult a qualified healthcare professional before starting any supplement.