This is a simple book recommendation for people who are interested in the physiological effects of stress. Robert M. Sapolsky wrote the highly readable and accessible Why Zebras Don't Get Ulcers in 1994, which is the edition I read, but Sapolsky has apparently issued two more updated versions, the latest in 2004.
The central argument of the book is that wild animals do not generally suffer chronic stress (except due to illness or famine) in the way humans do. Rather, animals suffer stress only when faced with an immediate danger to life and limb, as in when a predator is near. Then, the fight or flight instinct cuts in with all that entails physiologically - all bodily systems not directly involved in fighting or fleeing largely shut down and all energy is pumped into those parts of the body needed for survival.
Where animals experience the effects in the narrow area of threats from predators, humans experience stress in a much wider range of situations. Blessed, or burdened, with an intellect, humans can trick the body into thinking that non-physically threatening situations - paying the bills, demanding jobs, school exams - are in fact the same as being faced with a fight-or-flight situation. Only instead of being over once the physical threat has passed, humans can turn the endless stream of worry into chronic stress on the body. Physiologically, the body can be in near constant fight-or-flight mode. Sapolsky then describes the impacts of this chronic stress on each system of the body, concluding with a chapter on managing stress.
A wonderful read aimed at the layman. Alarming, but Sapolsky also manages to weave humour throughout the book. I can highly recommend this book.