Most people spend a third of their life sleeping - around 25 years or more!This series takes readers (Ages 8-12) on a historical journey, examining how people coped in the past and how they developed ingenious ways to make life safer and less unpleasant. Each book features full-color cartoon-style illustrations and hilarious speech bubbles to heighten interest, making the series attractive even to reluctant readers.Like it or not, we all have to sleep. Yet sleep is also very mysterious. No one really knows why we do it. And how do we explain all those strange dreams? What scientists do understand, however, is that sleeping is essential for health and happiness. Learn about the strange sleep cycles throughout the animal kingdom, and the theories behind why people get tired or have terrifying nightmares.