Stress-Response System

The stress-response system is a set of interacting biological pathways through which the body detects, interprets, and responds to challenge or threat to maintain stability. Central components include the autonomic nervous system (especially the sympathetic fight-or-flight response/FFR) and the hypothalamic–pituitary–adrenal (HPA) axis, which together regulate the release of stress hormones (such as cortisol) and coordinate changes in heartrate, attention, energy use, and immune activity. In the context of serious mental illness, the stress-response system is not simply reactive but often sensitized or dysregulated. Repeated or sustained stress — whether biological, psychological, or social — can recalibrate these pathways so that responses become exaggerated, prolonged, or less flexible. Over time, this can influence mood, anxiety, cognition, sleep, and even perception, while also interacting with systems like inflammation and cardiovascular regulation. Increasingly, research frames disturbances in the stress-response system as a shared underlying process that helps link mental and physical health, rather than as a secondary consequence of psychiatric symptoms alone.