Why do we sleep?

We spend around a third of our lives sleeping. But how does our body know when to switch off, and what 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 that, in our age of endless stimulation, has never felt so timely.