Why zebras don't get ulcers / Robert M. Sapolsky

A zebra chased by a lion walks away from the encounter without lasting harm, while a person stuck in traffic or fretting over a bill can end up with an ulcer. Robert M. Sapolsky takes up that contrast in a science book for general readers about what prolonged stress does to the human body and mind.

His starting point is that people switch on the same physiological alarm as other animals when they worry or feel threatened. An animal shuts the alarm off through a quick action such as fighting or fleeing. People usually do not, so the response stays active for months or years, and that chronic activation can make a person physically ill.

The book links long-term stress to a range of conditions, among them depression, ulcers, colitis and heart disease. It looks at how the nervous system reacts to stress and how those reactions can be brought under control, drawing on current research and offering practical advice along the way. The tone is light, with humor running through the science.

This is the thoroughly updated third edition. It adds new chapters on sleep disorders and addictions. Fresh sections cover gender differences, anxiety, weight gain, PTSD and managing stress. It suits readers who want to understand the biology behind stress and what they can do about it.