So a little stress is good. Some excitement or a new challenge rewires the brain in positive ways to help you learn and acquire new skills. But if the body is repeatedly stressed-out and anxious, when it is continuously bathed in cortisol rather than just spritzed now and then, all the finely tuned systems designed to protect the body begin to turn against it. That’s when it goes into what scientists call “allostatic overload.”8 That overload is not only shrinking our brains, it’s making us sick.
