The Cortisol Awakening Response
Your body shoots cortisol within 30 minutes of waking. If it doesn't, you're cooked.
Grounded in the research on Pruessner et al., "Free Cortisol Levels after Awakening," Life Sciences (1997)
1. The morning spike
The cortisol awakening response (CAR) is a sharp surge of cortisol your adrenal glands fire off the moment you wake up. It's separate from the slow background rhythm. Within 30 to 45 minutes of opening your eyes, cortisol climbs roughly 50 to 75 percent above your waking level, peaks, then falls back down. It's a distinct, measurable event every single morning.
2. Who clocked it
Jens Pruessner and colleagues first described it in 1997. They had people spit into tubes at waking, then +15, +30, +45 minutes. The pattern was so reliable it became a standard biomarker of HPA-axis function. Note: it's triggered by the act of waking, not by getting out of bed. The clock starts when your brain switches on.