Your stress system starts work about an hour before the time you expect to wake. Fifteen volunteers went to sleep in a lab after being told what time they would be woken. An hour before that time, with their eyes still shut, the hormone that calls for cortisol began to climb. When they were woken early by surprise, nothing had risen first. Their bodies had read the schedule.
Cortisol gets called the stress hormone and blamed for bellies, faces and burnout. It's made in the outer layer of two small glands that sit on top of your kidneys, and the names say so: "adrenal" means near the kidney, and "cortex" is the Latin for bark.
Its day job is to get you up: a sharp rise in the half hour after waking, a long slide through the day, and a low point late in the evening. The trouble starts when that curve goes flat, lower in the morning and higher at night. Across 80 sets of findings, a flatter curve went with poorer health, in body and in mood. Most advice on how to lower cortisol ignores the clock altogether. Ahead: how your body tells a workday from a weekend within minutes of waking, what coffee does to cortisol even when you drink it every day, the pace of exercise that sends it up by 83% and the half hour outdoors that brings it down, and what 58 sets of findings say about "adrenal fatigue".
1. Let the morning rise happen
The morning surge is preparation. When 196 British civil servants gave saliva on waking and half an hour later, the rise was bigger on workdays than at weekends, although they woke with the same level on both. The body loads up for the day it expects. The word for a daily rhythm like this, "circadian", comes from the Latin for "around a day".
A steep morning is the healthy half of the curve. The aim is a high start and a low finish.
Light helps the start. Eight men kept awake in dim light were switched to bright light early in the morning, and their cortisol jumped by more than half at once. The same light in the afternoon did nothing.
A bedside lamp can start the job before you open your eyes. Twelve people woken by a light that brightened over half an hour made more cortisol in their first 45 minutes awake, and felt more alert. That's what a does on a dark morning.
Get up when you wake, get into daylight as soon as you can, and give the first ten minutes to yourself before you give them to anyone else.
2. Drop the afternoon coffee first
Caffeine raises cortisol, and the habit only half cancels it. Ninety-six adults went five days without caffeine and were then given it through the day: cortisol climbed and stayed up. After five days of daily caffeine, the morning caffeine no longer moved it. The afternoon caffeine still did, and cortisol stayed raised until early evening, through the part of the day when the curve should be falling.
If you drink coffee, drop the afternoon one first, and see what your evenings feel like after a week.
3. Move at the right pace
Exercise can push cortisol either way. Twelve trained men did half an hour at three efforts. At the gentle one, cortisol barely moved. At the moderate one it rose by about 40%, and at the hard one by 83%. A spike after hard effort is normal, and it passes. The question is what else the day has already asked of you.
Over weeks the picture turns round. Across ten tests, people who took up regular physical activity ended with lower cortisol and better sleep than those who stayed as they were.
Where you move matters too. Thirty-six city dwellers were asked to spend time somewhere that felt like nature at least three times a week. Time there brought cortisol down by about 21% an hour, beyond its normal fall for that part of the day, and twenty to thirty minutes gave the most for the time spent.
On a day when you already feel wrung out, swap the hard session for a walk somewhere green.
4. Skip the sugar fix
Sugar does turn the alarm down. Nineteen women drank sugar-sweetened or artificially sweetened drinks for two weeks, and only the sugar group produced less cortisol under stress afterwards. The relief is real and short, and it teaches you to come back for more.
When stress has you reaching for something sweet, walk for ten minutes first.
5. Watch the drink
Alcohol feels like the off switch, and the curve says otherwise. Among 3,670 civil servants, men's cortisol ran about 3% higher for every unit of alcohol they drank in a week, and in heavy drinkers the daily slide from morning to night was flatter.
Take one week without alcohol and compare how you wake. If you drink heavily every day, stopping overnight can be harmful, so get help to cut down.
6. Guard the night
One short night shows up the next evening. Young men kept to four hours in bed had 37% more cortisol the following evening than after a full night, and with no sleep at all it was 45%. The quiet stretch that should begin in the evening started at least an hour late.
So a bad night makes the next night harder, which is how a flat curve builds.
Night shifts push against the clock itself. Hair from 33 shift workers held about 60% more cortisol than hair from 89 day workers, and the gap sat with the younger ones. If you work nights, a dark room for your sleep matters twice over.
After a short night, go to bed early the next evening, and leave the catching-up for the pillow. A keeps an early summer dawn from cutting the night short.
7. Breathe slower
Breathing is the one part of the stress response you can take over by hand. Forty adults were split in two, and half were trained in slow belly breathing, about four breaths a minute, in twenty sessions over eight weeks. Their cortisol came down and their mood lifted. The untrained half stayed where they were.
Breathe in through your nose into your belly and out slowly, a few breaths a minute. Practise when you're calm, so it's there when you're not. James Nestor's is a whole book on what slow breathing does.
8. Bring someone with you
Thirty-seven men were told they had to give a talk in front of a panel, a standard way of stressing people in a lab. Those who prepared with their best friend beside them produced less cortisol than those who prepared alone.
A dog works too. Forty-eight people faced the same kind of test with a friend, with a dog they had never met, or alone. The dog group's cortisol stayed lowest throughout.
So does laughing. Across eight tests in 315 people, a spell of real laughter, usually a comedy video, cut cortisol by about 32%.
Before the next thing you dread, spend ten minutes with someone on your side.
Do meditation and yoga work?
It helps most where the strain is greatest. Across 31 tests, meditation lowered cortisol clearly in people who were ill, probably in people living under heavy stress, and only slightly, if at all, in everyone else.
Yoga has the stronger record. Across 42 tests, practices built on yoga postures lowered cortisol, in the evening and on waking, when measured against another activity.
Does fasting raise it?
At first, yes. Across 13 tests in 357 people, going without food pushed cortisol up sharply, ordinary calorie cuts did not, and the rise faded over several weeks.
Is "cortisol belly" real?
The link is. Among 59 women, those who carried their fat at the waist released more cortisol under stress in the lab than those who carried it at the hips, and the lean ones among them never got used to the same stress repeated. Which comes first is still unsettled. The "cortisol face" of social media borrows a sign of Cushing's syndrome, covered below.
What about "adrenal fatigue"?
Long stress wears the adrenal glands out, the story goes, and a saliva kit and a tub of capsules will fix it. Reviewers went through 3,470 papers and found 58 that tested the idea properly. Their conclusion is in the title: adrenal fatigue does not exist.
Your tiredness is real. The explanation is wrong, and so is the bill.
A single reading mostly tells you what time it was. Cortisol runs high in the morning and low at night in a healthy person, so one sample can look high or low with nothing wrong.
Hair keeps a longer record, months of it. Across 66 sets of findings in 10,289 people, those living with ongoing stress carried 43% more cortisol in their hair. Those whose stress was behind them carried no extra at all.
Before you pay for a cortisol test or an "adrenal" supplement, work on the eight things above for a month.
What about ashwagandha?
It's the herb with the most tests behind it. Across 12 of them, in 1,002 people, it lowered stress and anxiety more than a dummy pill, though the reviewers rated the certainty as low. In one 60-day test of 60 stressed adults, morning cortisol fell further on the herb than on the dummy. Treat it as a modest help for some people, after the habits above.
It has been tested for up to about three months, so long-term safety is unknown. Rare cases of liver injury have been linked to it. It's one to avoid in pregnancy and while breastfeeding, and with thyroid or autoimmune conditions, and it can interact with medicines for diabetes, blood pressure, thyroid and sleep.
When it's a disease
The same hormone is one of the great medicines. In 1949 a close relative of it, cortisone, got people crippled by rheumatoid arthritis moving again, and it won a Nobel Prize the following year. Cortisol itself was filed under the plain name "compound F".
Two conditions sit at the ends of the scale, and a busy life causes neither. Cushing's syndrome is too much cortisol, most often from taking steroid medicine for a long time. Fat gathers on the neck, upper back, chest and tummy while the arms and legs stay thin, the face turns round and red, and the skin bruises easily. If you take steroid medicine, never stop it suddenly; that can be dangerous.
Addison's disease is too little. The signs are extreme tiredness, patches of darker skin, weight loss, a craving for salt and dizziness on standing up. John F. Kennedy lived with it through his presidency. Either pattern needs a blood test.
A curve you can steepen
Cortisol is a clock as much as an alarm. It read tomorrow's wake-up time in fifteen sleeping volunteers, and it reads yours.
Give it a clear morning and a quiet night, and let it do the rest.
Want to know what long stress does to the rest of you? Stuck in Survival Mode: What Chronic Stress Does to the Body — the heart, the gut, the immune system and the belly, and what sounds the all-clear.
Thinking of cutting the coffee? How to Quit Coffee: Getting Through Caffeine Withdrawal — what withdrawal feels like, and how to step down without the headache.
Know someone who is tired all day and wide awake at night? Send them this.
Disclaimer: This article is general information. For advice about your own health, talk to a qualified health professional.
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