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Cortisol: what the stress hormone does to skin, sleep and energy

Take a saliva sample from a healthy adult at seven in the morning, then another from the same person at ten at night. The two numbers can differ by a factor of ten. Nothing has gone wrong. That is what a working cortisol rhythm looks like.

Which is the first useful thing to say about cortisol: a single measurement tells you almost nothing. The shape of the curve across the day carries the information, and the shape is what the popular conversation leaves out.

The short version

• Cortisol is a daily curve, not a single number. It peaks around your habitual waking time and should reach its lowest point late in the evening, where overnight repair happens and which is the first part of the curve to go when sleep runs short.

• The nuance that matters most: a flattened curve is associated with poorer health, but the link is small, r = 0.147, and mostly cross sectional. What is well established is that short sleep raises evening cortisol and that the skin barrier repairs itself overnight.

• Sleep, daylight and caffeine timing move the curve; nutrition is the part you can keep constant. Health Royals Peak Performance Formula, a daily multivitamin for women, carries Extramel® melon extract at 10 mg, the dose in two placebo-controlled studies on perceived stress, fatigue and sleep-related problems.

Health Royals Peak Performance, supplement with vitamin D3, K2 as MenaQ7, folate as Quatrefolic and omega-3 from algal oil

A daily base while the curve recovers

Peak Performance is our daily multivitamin for women with omega 3 from algae, the nutritional base you can keep constant every day. It carries Extramel® melon extract at 10 mg, the daily dose in its two placebo-controlled human studies, with vitamin D3, B12 as MecobalActive® and folate as Quatrefolic®. Vitamin B12 contributes to the reduction of tiredness and fatigue. Vitamin D contributes to normal muscle function.

See Peak Performance, multivitamin for women with omega 3

What is cortisol, and why is it not the enemy?

Cortisol is a glucocorticoid hormone made in the adrenal cortex, and its job is to hold blood glucose, blood pressure and immune activity inside a workable range from one hour to the next.

It is released by the hypothalamic pituitary adrenal axis, and belongs to the signalling molecules usually called stress hormones. Adrenaline handles the first seconds of a threat, cortisol the hours that follow. We have written about that longer arc in a separate piece on stress and sleep.

Both extremes are genuine disease. Sustained glucocorticoid excess is Cushing's syndrome, which the Endocrine Society guideline puts at roughly two to three cases per million people per year in Europe. Sustained deficiency is adrenal insufficiency. Both are diagnosed with laboratory tests, not with lifestyle. The interesting question is not how much cortisol you have, but when.

How does a normal cortisol curve look over 24 hours?

It peaks around the time you habitually wake, declines through the day, and reaches its lowest point in the late evening and the first hours of the night.

On top of that slope sits a separate event: within the first hour after waking there is an additional rise, the cortisol awakening response, which a review in Current Opinion in Endocrine and Metabolic Research describes as separate from the increase during the second half of the night and, unusually, as largely independent of circadian control.

The floor matters as much as the ceiling. The same review places the circadian nadir across roughly four to six hours in the late evening and early night. That trough is when most overnight repair happens, and it is the first part of the curve to go when something is genuinely wrong. Clinicians use exactly that: one of the four recommended first line tests for cortisol excess is a late night salivary sample.

What raises cortisol during the day?

Waking, acute psychological stress, hard training, large doses of caffeine and short sleep, and only the last two are easy to change.

Acute social stress is the best characterised. A meta-analysis of 76 sub-studies covering 5,171 people used the Trier Social Stress Test, in which people give an unprepared talk to an unresponsive panel. The average salivary cortisol response was d = 0.93, with peaks averaging 17.15 nmol/l in men and 10.87 nmol/l in women.

That is a large and reliable rise, and a normal one: in healthy people it resolves within the hour. A cortisol response to a stressful event is the system working, not failing.

Caffeine is more specific than its reputation. A randomised crossover trial in Sleep gave 23 healthy men 100 mg or 400 mg of caffeine at 12, 8 and 4 hours before bed. The 100 mg dose produced no significant sleep disruption at any timing. The 400 mg dose, about four strong coffees, delayed sleep onset by 14 to 25 minutes and cut deep sleep by 15 to 30 minutes. That is a sleep effect rather than a direct cortisol effect, but short sleep is itself a cortisol input.

Why do you wake up tired after a full night in bed?

Usually because the evening trough never arrived, not because the morning peak was too low.

In a controlled study in Sleep, young men deprived of sleep had cortisol levels 37 and 45 percent higher the following evening, measured between six and eleven at night, with the normal nightly decline delayed. The morning looked ordinary; the evening did not.

Chronic restriction produces the same shape. Sleeping 5.5 hours or less raises late afternoon and early evening cortisol without necessarily changing the 24 hour total. The area under the curve looks unremarkable while the curve has flattened.

Sleep loss is not a niche problem. In Folkhälsomyndigheten's 2024 national public health survey, sent to more than 110,000 adults, around 45 percent reported sleep problems. The response rate was close to 40 percent, down from 61 percent in 2004, so the figure is not precise. The agency publishes the sleep statistics.

As for what a flattened curve is associated with, a meta-analysis of 80 studies and 179 separate associations found flatter slopes linked to poorer outcomes in 10 of 12 categories of emotional and physical health, with an overall effect of r = 0.147. The strongest link was with immune and inflammatory markers, r = 0.288. Read that carefully: r = 0.147 is small, most of the work is cross sectional, and association is not causation. The flattened curve may be a readout of poor health rather than a driver of it.

Here is what we do know. Short sleep reliably raises evening cortisol, and the evening trough is where repair happens. That makes the evening the place to start, and daytime tiredness something to act on rather than measure. More on recovery in our wellbeing section.

Can cortisol and stress be seen in the skin?

There is a measurable effect, but on how quickly the skin barrier repairs itself, not on how tired your face looks the next morning.

A study of 60 healthy women in Clinical and Experimental Dermatology compared poor sleepers with good sleepers. Poor sleepers had higher baseline transepidermal water loss. Seventy two hours after the barrier was deliberately disrupted by tape stripping, good sleepers had recovered about 30 percent more. They also scored better on intrinsic ageing measures and recovered faster from ultraviolet induced redness.

Sleep quality was self reported, and the design looks at sleep as a whole rather than at cortisol alone.

What it supports is a mechanism people underrate: barrier repair is largely an overnight job, and protecting the evening reaches the skin from the inside. The barrier itself is covered in our article on the biology of radiant skin.

Can you measure your own cortisol, and does anything lower it?

You can buy a number, but the curve carries the meaning, and reading it is a clinical job.

A 2025 review of the cortisol axis in Pharmacological Reports concludes that cortisol alone may not serve as a reliable biomarker, because what a value means depends heavily on the condition and the person. Hair cortisol, marketed as a reading of chronic stress, has limits which a review in the Journal of Sports Science and Medicine lists: only weak correlations with perceived stress, elevation from regular vigorous exercise regardless of psychological load, and low to moderate agreement with saliva, plasma and urine. If you suspect something is genuinely wrong, healthcare has both the tests and the interpretation.

Among supplements, ashwagandha is the most studied candidate. A 2025 systematic review in BJPsych Open pooled 15 randomised trials and 873 participants and reported reductions in both perceived stress and measured cortisol at eight weeks. The trials are small, short and heterogeneous, and a change in a laboratory value is not the same as a change you feel.

Peak Performance is built for something else: making sure the nutritional base is in place every day, with each ingredient there for a documented reason.

What actually helps an overloaded nervous system?

The measures with the best support are simple: one consistent wake time, daylight early, caffeine kept to the first half of the day, and enough sleep for the evening trough to happen.

  • Keep one wake time, weekends included. The awakening response is anchored to habitual waking, so a wake time that moves by three hours leaves nothing to anchor to.
  • Get outside early. Daylight in the first hour is the strongest signal that the day has started, and in a Swedish winter the scarcest.
  • Move the caffeine rather than removing it. In the trial above, 100 mg carried no measurable cost at any timing. 400 mg needed a full 12 hours.
  • Train, and stop worrying that it raises cortisol. It does, acutely, and that rise is part of the training stimulus, not a side effect.
  • Defend the last two hours of the evening. The trough is the point of the whole curve.

Sleep and daylight move the curve. Nutrition is the one item on the list you can keep constant when everything else slips, and the Nordic Nutrition Recommendations 2023 set the reference values a daily intake should cover. That is what Peak Performance, multivitamin for women with omega 3, is for: one jar, every morning, while you work on the parts that move the curve.

The ingredient closest to this article is Extramel®, a melon extract rich in the enzyme superoxide dismutase, made by Robertet in France and tested in two placebo-controlled human studies. In the first, published in Nutrition Journal in 2009, 70 participants took 10 mg of Extramel or placebo daily for four weeks; the study measured perceived stress, fatigue and sleep-related problems, and the Extramel group reported a 38 percent greater improvement in sleep-related problems than placebo. The second, in Nutrients in 2014, followed 61 participants for 84 days on the same kind of outcomes; both are described in our article on melon SOD, oxidative stress and recovery. Extramel was studied at 10 mg per day. Peak Performance contains 10 mg per daily dose. For us, the ingredient cannot be separated from its source, manufacturer and studied dose.

The vitamin claims on tiredness are precise. Niacin and vitamin B12 contribute to normal energy-yielding metabolism, and niacin, folate and vitamin B12 contribute to the reduction of tiredness and fatigue. Peak Performance carries vitamin B12 as MecobalActive® methylcobalamin, 10 µg, folate as Quatrefolic® 5-MTHF, 200 µg, and niacin 16 mg, at a nutritional level. For us, the dose is as important as the raw material, and covering the reference value every day is the job.

Vitamin D contributes to normal muscle function and to the normal function of the immune system. Peak Performance contains 25 µg of vitamin D3 as Quali-D®, a middle ground for use all year, explained in our article on vitamin D deficiency. DHA contributes to the maintenance of normal brain function, and OMEGATEX® algal oil gives 300 mg of DHA a day. K2 as MenaQ7®, Hytolive® olive fruit extract at 15 mg hydroxytyrosol, the daily amount in its placebo-controlled human study, zinc, selenium and chromium complete the jar. A base only works if it is taken every day, so the jar is amber glass with a scent core, made to stand on the counter, with refill pouches by subscription.

We have done the selection so that you do not have to. Peak Performance is the part of the list you can keep constant while the evening trough comes back. Real recovery over hours and days is the subject of our article on stress and sleep.

Further reading

Frequently asked questions

How do I know if my cortisol is high?
A single value tells you almost nothing; the shape of the curve across the day carries the information. Genuine cortisol excess is Cushing's syndrome, an uncommon condition investigated in healthcare with tests that include a late night salivary sample. If something feels wrong, ask for an investigation.

What does a home saliva or hair cortisol test tell me?
A value, without the curve that gives it meaning. Hair cortisol correlates only weakly with perceived stress and is raised by regular vigorous exercise, and a 2025 review concludes that cortisol alone may not serve as a reliable biomarker.

Does ashwagandha lower cortisol?
A systematic review of 15 randomised trials and 873 participants reported lower measured cortisol at eight weeks. The trials are small, short and heterogeneous, and a laboratory value that changes is not the same as a change you experience.

Is cortisol face a real thing?
No, there is no recognised condition by that name. Facial fullness from genuine glucocorticoid excess is a clinical sign of Cushing's syndrome, diagnosed with laboratory tests; puffiness after a bad night is something else.

Should I give up coffee because of cortisol?
Dose and timing matter far more than coffee itself. In a randomised crossover trial, 100 mg of caffeine produced no significant sleep disruption at any timing, while 400 mg delayed sleep onset by 14 to 25 minutes and needed twelve hours of margin. Move the caffeine to the first half of the day.

Where does Peak Performance fit in?
As the daily base you can keep constant while you work on the measures with the best support: a consistent wake time, daylight early and enough sleep. It contributes nutrition: vitamin B12 contributes to the reduction of tiredness and fatigue, and Extramel® sits at 10 mg, the dose in two placebo-controlled studies on perceived stress, fatigue and sleep-related problems.

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