Cortisol awakening response

The cortisol awakening response (CAR) is a sharp rise in salivary cortisol of roughly 50 percent on average (commonly reported in the range of about 38 to 75 percent) from the awakening sample to a peak about 30 to 45 minutes after waking. It reflects healthy hypothalamic-pituitary-adrenal axis activation, mobilising energy and focus for the day. A blunted or exaggerated CAR is associated with chronic stress, burnout, depression, sleep disorders, and adverse cardiometabolic outcomes, making it a useful marker in longevity and stress research.