Stress and the Stress Response(4 expert discussions analyzed)

When a situation feels challenging or threatening, the body switches on a fast alarm response: heart rate and blood pressure rise and energy is released. The brain also activates the hypothalamic-pituitary-adrenal (HPA) axis, which tells the adrenal glands to release more cortisol, a hormone that makes glucose and fat available for energy and helps regulate immunity and inflammation. Cortisol normally peaks after waking and falls through the day. Once the pressure passes, the body returns to normal (APA).

Stress usually fades once the situation is resolved. It becomes a concern when it is ongoing, when it no longer eases, or when it starts to affect sleep, mood, concentration or behaviour, for example irritability, changes in appetite or drinking and smoking more (NIMH; NHS). Anxiety differs from stress in that it can continue even when there is no current threat (NIMH). If stress persists, feels unmanageable or interferes with daily life, it is worth talking to a doctor (NHS).

Cortisol is essential, and its levels rise and fall normally with stress, illness and the time of day. Truly excessive cortisol (Cushing's syndrome) is uncommon, and steroid medicines are its most common cause. Endocrinology guidance recommends testing only people with specific features, such as unusual findings for their age or several progressive signs, and recommends against widespread testing (Endocrine Society 2008). Too little cortisol (adrenal insufficiency) is also uncommon; it is a real medical condition that needs testing by a doctor when it is suspected. "Cortisol face" is not a medical term; a puffy or rounder face has many causes.

The Endocrine Society states that there is no scientific proof that adrenal fatigue is a true medical condition, and that tests sold for it are not based on sound science. Supplements marketed for it may be harmful: taking adrenal hormones you do not need can stop your own adrenal glands working and lead to a life-threatening adrenal crisis. Tiredness, weakness or low mood deserve a proper diagnosis, as they can come from conditions such as depression, sleep apnoea or true adrenal insufficiency (Endocrine Society).

Long-term stress is linked to poorer health, but most of the evidence is observational. Across nearly 200,000 European employees followed for about seven years, people reporting high work strain had about a 23% higher rate of a first heart attack or coronary death than those without it (17% higher after accounting for socioeconomic status). This is an observational link, not proof of cause. The researchers also estimated what this means across the whole working population: if the link were causal, work strain would account for about 3% of these heart events, compared with about 36% for smoking. These are population-level estimates that depend on how common each factor is; they are not a comparison of one person's risk from stress and from smoking (Kivimäki 2012). Stress is also linked to headaches, back pain, worse asthma, gut symptoms such as irritable bowel syndrome, and changes in sex hormones (APA). Some of these links may run through sleep, alcohol, smoking or inactivity, and stress is not shown to be the hidden cause of conditions such as thyroid disease or menopause symptoms.

The World Health Organization defines burnout as a syndrome resulting from chronic workplace stress that has not been successfully managed, with three features: exhaustion, mental distance or cynicism about the job, and reduced effectiveness at work. It applies only to work and is not classified as a medical condition (WHO 2019). Burnout and depression share symptoms, so if you feel low or have lost interest in things for more than two weeks, see your doctor.

In trials, structured stress-management courses, relaxation-based approaches and mindfulness courses reduced stress or distress by small to moderate amounts; the evidence is mostly low certainty and comes largely from specific groups such as healthcare workers (Tamminga 2023, Cochrane; Galante 2021). Physical activity also reduced distress (Singh 2023). Resilience training and breathing exercises show smaller or less certain effects (Kunzler 2020; Fincham 2023). Social connection matters too: loneliness and social isolation are linked to higher mortality in long-term studies, although these studies cannot prove cause (Holt-Lunstad 2015).