Psychological trauma is among the most devastating of conditions. Though classified as a mental health disorder, it affects the body at the most fundamental levels. This monograph traces the physiological roots of posttraumatic stress disorder in the body’s many systems: the brain, the autonomic nervous system, the endocrine system, and the many organs they control. It weaves together the most current research from many different scientific fields. It’s a unique resource for scholars, therapists, physicians, and journalists — as well as patients who wish to understand the underlying physiology of stress.