Everything you ever wanted to know about sleep but were too exhausted to ask.We spend around a third of our lives sleeping. But what actually happens during those hours? This book takes you on a fascinating journey through the land of nod and out the other side. •    What are circadian rhythms and how do they affect our energy levels throughout the day?•    What are dreams for and how do they happen?•    What are the different stages of sleep?•    Do animals experience sleep the same way we do?With clear texts and bright, distinctive illustrations, this is a great introduction to a subject that has fascinated us since ancient times, and an engaging tie-in to biology and natural sciences curriculums.