Why we need to sleep is not actually known, but it is a topic that continues to intrigue us. The author takes an historical approach to the subject and presents a largely chronological view of sleep research. Parts one and two describe the main historical figures and their various theories and discoveries. Part three describes our current state of knowledge of sleep and waking. This book is readable by anyone who has some introductory biology or psychology, it will also make an excellent book for anyone taking a course on sleep.