The autonomic nervous system and the adrenal cortex. Homeostasis is taught as a textbook fact, the body reverting to a baseline over time. What’s not taught is how much the impacts of daily life events drive a continuous stress response. Fight or flight is not just a reaction to deadly threats. It’s active every moment of every day to ensure survival. The adrenal cortex is always active, to traffic, your boss and colleagues, relationship struggles, and overall health and wellness like sleep and nutrition. Yes, the system reverts to a baseline over time but how much that baseline varies is obvious in tracking resting heart rate.