Why do we sleep? How much sleep do we really need? What causes sleep apnea, narcolepsy, and insomnia--and what can be done about these sleep disorders? Why do older people have more trouble sleeping than young people? We have all puzzled over--or been plagued by--the mysteries of sleep. Now a leading researcher on sleep provides an engaging and informative introduction to the subject that answers many of our questions.

Peretz Lavie surveys the entire field of sleep research and sleep medicine--from the structure of sleep stages and the brain centers involved in sleep regulation to the...