ABSTRACT The Nightmare, by Ernest Hartmann, despite its subject's gruesome and unpleasant connotations, is a delight to read. It is written by an expert in the fields of the physiology and psychology of sleep. Dr Hartmann deals with some quite technical matters, yet the lucid presentation makes it informative and pleasurable for the professional and layperson alike.The basic data for the book were obtained from groups of people recruited from newspaper advertisements who had a history of lifelong, continuing, and frequent nightmares. The controls were from past studies of similarly recruited people. These groups were given psychiatric interviews as well as psychological tests, including the Rorschach Ink Blot, Thematic Apperception, Minnesota Multiphasic Personality, Cornell Index, and the Fear Survey. A few of the subjects were also studied in the sleep laboratory. The results were carefully analyzed and statistically validated before conclusions were drawn.The index cases had distinct psychological patterns