Sleep is as important to the human body as food and water. Recent research suggests that those who get less than the recommended eight hours a night are more likely to become sick and die sooner than their well-rested counterparts. Though there is much about sleep that remains a mystery to scientists, there is mounting evidence of health risks as more and more Americans cut back on needed rest and bad sleep habits are being passed on to children. ''Sleep Disorders'' is a concise guide to sleep and sheds helpful light on how it functions and how it can be disrupted.Coverage includes sleep disorders such as insomnia, snoring, sleep apnea, restless leg syndrome, narcolepsy, and sleepwalking. Sleep's relationship to chronic illnesses such as heart disease, arthritis, and diabetes is also discussed. Chapters include: What Is Sleep?, Insomnia, Sleep Apnea, Movement Disorders, Narcolepsy, andChildhood Sleep Disorders.