Cortisol & The HPA Axis: The Biology of Chronic Stress
The hypothalamic-pituitary-adrenal axis is the body's master stress response system — a hormonal cascade that evolved for short-term survival threats but is chronically activated by the psychological, nutritional, and environmental stressors of modern life, creating a sustained cortisol elevation that suppresses immune function, disrupts the gut microbiome, promotes visceral fat deposition, impairs hippocampal neurogenesis, and accelerates cellular ageing through telomere shortening. Understanding the HPA axis — its feedback loops, its interaction with the thyroid and sex hormone axes, and its susceptibility to disruption by inflammatory cytokines, nutritional deficiencies, and environmental toxins — is essential for addressing the fatigue, anxiety, hormonal dysregulation, and immune collapse of modern chronic disease.
