Burnout and cortisol: what the research shows

Burnout does not have a single cortisol signature. It is tempting to assume that months of work stress push cortisol up, or that the system eventually "burns out" and cortisol drops, but studies of long-term cortisol in hair have not settled the question. One study of care workers found that more burnout symptoms went with higher hair cortisol, in a non-linear way,¹ another found that an imbalance between effort and reward at work predicted lower, blunted long-term cortisol,² and a 2026 review of 111 studies concluded that no biological marker is good enough to diagnose burnout.³ Hair cortisol is a useful research measure of long-term stress physiology, but it is not a burnout test.

What burnout is, and what it is not

The World Health Organization describes burnout as a syndrome resulting from chronic workplace stress that has not been successfully managed. It has three features: exhaustion or depleted energy; growing mental distance from your job, or negative and cynical feelings about it; and reduced effectiveness at work.⁴ In the International Classification of Diseases, the WHO lists burnout as an occupational phenomenon, not a medical condition, and says the term should be used only for work, not other areas of life.⁴

Burnout is also not the same as:

• "Adrenal fatigue". The idea that stress wears out the adrenal glands is not supported. The Endocrine Society says there is no scientific proof that adrenal fatigue is a real condition, and that no test can detect it.⁵ See adrenal fatigue.
• Depression or a physical illness. Exhaustion, poor sleep and low mood overlap with depression, and with conditions such as adrenal insufficiency and obstructive sleep apnoea, which the Endocrine Society lists among the real causes of symptoms often blamed on adrenal fatigue.⁵

That overlap is one reason to see a GP if exhaustion does not lift. If you ever feel you might harm yourself, treat it as an emergency: call 999 in the UK or 911 in the US, or go to an emergency department.

Why cortisol is linked with stress and burnout

Cortisol is the end product of the body's main stress system, the hypothalamic-pituitary-adrenal (HPA) axis. A stressor sets off a chain of hormones from the brain to the adrenal glands, and cortisol then switches the response off again by feeding back on the brain.⁶ Chronic stress can change this system in different ways, from constant oversecretion to an exaggerated response, depending on how long, how intense, how frequent and what type the stress is, and on the person's genes, early life, sex and age.⁶ That variety is part of why burnout does not map onto one cortisol pattern.

Across stress research more broadly, a meta-analysis of 66 studies and more than 10,000 people found hair cortisol 22 per cent higher in groups exposed to chronic stress, and 43 per cent higher where the stress was still going on, while past stress showed no significant difference.⁷ The same analysis found hair cortisol was not consistently related to how stressed people said they felt.⁷ Our guide to cortisol and stress covers this in more depth.

What hair cortisol studies of burnout have found

Hair is the natural sample for burnout research, because burnout builds over months and hair records months of cortisol in one sample. The results so far are mixed:

• Care workers. In 194 employees in geriatric care, most of them nurses, overall burnout symptoms had a non-linear (exponential) relationship with hair cortisol taken six months later: higher symptoms went with higher cortisol, more steeply at the top end. But no single part of burnout, such as exhaustion, was related once other factors were taken into account.¹
• The Dresden Burnout Study. In 150 people followed over two years, effort-reward imbalance at work, meaning putting in high effort for little reward, predicted lower, blunted long-term cortisol.²
• A 2026 systematic review. Across 111 studies and 36 different biomarkers, links between the HPA axis and burnout were inconsistent, and no biological signature was good enough for routine diagnosis.³

So a high hair cortisol result does not mean you are burnt out, and a normal or low one does not mean you are not. Burnout is recognised by how you are feeling and functioning at work, not by a laboratory value.

Work stress, unemployment and shift work

Some work-related situations show up more clearly in long-term cortisol. Long-term unemployed people had higher hair cortisol across 6 cm of hair than people in work, even though their self-reported stress was not related to it.⁸ In a study of 33 shift workers and 89 day workers, hair cortisol averaged 47.32 against 29.72 pg/mg. The difference was found only in younger workers (48.53 against 26.42 pg/mg), and the younger shift workers also had a higher body mass index.⁹

Shift work also disturbs the daily rhythm of cortisol: sudden changes to the sleep-wake cycle activate the HPA axis and change its usual pattern.¹⁰ Lost sleep matters too. After partial or total sleep deprivation, cortisol the next evening was 37 and 45 per cent higher respectively.¹¹ See cortisol and shift work and cortisol and sleep.

What can help

The most useful evidence comes from controlled trials that measured hair cortisol before and after a change:

• Meditation-based mental training. In the ReSource trial, 362 people were randomised and hair data were available for 227. Hair cortisol and cortisone fell consistently over the first 3 to 6 months of training, with no further fall by 9 months. The effect grew with how often people practised, and it was unrelated to changes in how stressed they said they felt.¹²
• Aerobic exercise. In a 12-month trial in 130 adults aged 26 to 58, 150 minutes a week of moderate-to-vigorous exercise lowered hair cortisol compared with a group given health information instead, although other stress and heart-related markers did not change consistently.¹³
• Treating insomnia. In 74 shift-working nurses, a digital cognitive behavioural therapy programme for insomnia improved sleep markedly, and hair cortisol fell by 44 per cent within the group that had the programme.¹⁴
• Support from others. In a laboratory study, support from a close friend lowered the cortisol response to a stressful task.¹⁵

A review of 14 studies with 1,916 participants found the effects of relaxation, mental training and psychological therapy on hair cortisol were mixed, so these results are encouraging but not uniform.¹⁶ And because the WHO defines burnout by chronic workplace stress that has not been managed,⁴ it makes sense to look at the work itself, such as workload, control and support, with your employer, occupational health or a GP. Our guide on how to lower cortisol covers the wider evidence.

Where a hair cortisol test fits

A hair test measures your average cortisol over roughly the past three months from one sample: scalp hair grows about 1 cm a month, and the 3 cm nearest the scalp are usually tested.¹⁷ Because it averages out the daily ups and downs, it is consistent. In one study a person's hair cortisol correlated at r = 0.84 from one month to the next, against 0.38 to 0.61 week to week for saliva.¹⁸ That makes it the most accurate way to measure long-term cortisol from a single sample, and it is why researchers use it in burnout studies.

What it can show is whether a demanding period has registered in your cortisol and, if you test again a few months after making changes, whether your levels have moved. What it cannot show is whether you have burnout, depression or any other condition: the research finds no consistent burnout pattern, and both raised and blunted cortisol have been reported.³² Treat a result as one piece of information about your stress physiology, alongside how you feel, and talk to a GP if you are struggling.