Recently, scientists discovered that they had overlooked a key step in the stress response: in the first half hour or so following a stressor, the body’s immune system becomes more active. This makes evolutionary sense—the body is preparing for a wound or possible infection, say. Then, over the following hours, the body typically tries to return immune activity to a baseline, by releasing steroid hormones to inhibit white blood cell production. But some people get stuck in the heightened
