That's one of those books when you think what's there to know about sleep. Turns out a lot. The book is an overview of the current research about sleep. There are a lot of references and details, so be prepared for a long read.
Before reading the book I already saw sleep as one of the most important activities. After reading it, I definitely underestimated it.
I would recommend this book to everyone. I think it's important to understand and appreciate the power of sleep.