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Sleep & circadian

Cortisol awakening response

DECortisol-Aufwachreaktion

The cortisol awakening response (CAR) is a sharp rise in your salivary cortisol right after you wake up. On average it climbs about 50% (commonly reported between roughly 38 and 75%), from the waking sample to a peak about 30 to 45 minutes later. It reflects a healthy morning kick from your HPA axis (the hypothalamic-pituitary-adrenal stress system), mobilizing energy and focus for the day. A CAR that is too flat or too exaggerated is tied to chronic stress, burnout, depression, sleep disorders, and worse cardiometabolic outcomes. That makes it a useful marker in longevity and stress research.

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Sources

  1. Pruessner JC, Wolf OT, Hellhammer DH et al.. (1997). Free cortisol levels after awakening: A reliable biological marker for the assessment of adrenocortical activity. *Life Sciences*doi:10.1016/S0024-3205(97)01008-4
  2. Clow A, Thorn L, Evans P, Hucklebridge F. (2004). The awakening cortisol response: methodological issues and significance. *Stress*doi:10.1080/10253890410001667205