The Hidden Cost of Everyday Stress: How Chronic Activation of Fight-or-Flight Affects Health

When a stressor appears, the body triggers a fight-or-flight cascade: adrenaline spikes within seconds, raising heart rate, blood pressure and breathing; cortisol rises about 30 minutes later, regulating pressure, suppressing inflammation and mobilising glucose. Prof Kavita Vedhara of Cardiff University notes the system evolved for physical threats like predator attacks.

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Repeated activation diverts resources from digestion, repair and immunity. Studies link chronic stress to weakened immune function, higher infection risk, reduced vaccine efficacy, slower wound healing, obesity, depression and faster progression of neurodegenerative diseases such as Alzheimer’s. Dr Jo Daniels of the University of Bath explains that hyper-vigilance makes normal bodily sensations feel threatening, amplifying anxiety and impairing decisions.

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Slow, regulated breathing signals safety to the brain, breaking the threat loop; exercise dissipates excess adrenaline. For persistent stress, cognitive-behavioural therapy targets unhelpful thoughts, while mindfulness-based stress reduction teaches stepping back. Lifestyle changes, social support and early recognition further reduce risk.

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Trauma survivors often have lower stress thresholds, whereas some thrive in high-stress careers. Daniels notes that life experiences and learned resilience shape personal limits. A minority argue that moderate stress (“eustress”) can boost performance, highlighting a nuanced view of stress’s role.

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Vedhara notes chronic activation blocks the elastic stress system’s recovery; Daniels adds that breathing, exercise and therapy restore balance. A 1990s study of 398 volunteers linked stress to higher cold susceptibility, and only about 6 % of UK respondents say they never feel stressed. They advise seeking professional help when stress is pervasive.

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Researchers have not defined a stress frequency or intensity threshold that guarantees health harm, leaving a gap in guidelines for when acute stress becomes chronic.

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• “The most immediate effect we see in a stressful situation is a surge of adrenaline causing an increase in heart rate, blood pressure and breathing,” — Prof Kavita Vedhara, Cardiff University

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• “Perhaps the most well-known issue associated with chronic stress is poorer immune function, which can increase risk of infections, make vaccines work less well, impair wound healing, and so on,” — Prof Kavita Vedhara

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• “If you breathe slowly, you’re giving your brain the message that everything is OK, you are safe – essentially inducing the relaxation response.” — Dr Jo Daniels

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• “Catch your stress response early, and you have a good chance of reversing it using simpler strategies – but for chronic stress, modifications to lifestyle, accessing social support and developing helpful coping skills are key,” — Dr Jo Daniels

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Future research aims to quantify stress thresholds and identify biomarkers for early detection. Public-health programmes are expected to promote breathing and mindfulness training in schools and workplaces, while clinicians are urged to screen for chronic stress during routine visits.

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