Sleep is a wonderland of mystery. Why do we need so much of it? Why do we dream? How am I still awake after lying in bed for 6 hours praying for the sweet release of unconsciousness? These are just a few of the questions that Penelope A. Lewis has studied as director of the Sleep and Memory Lab at the University of Manchester, and in The Secret World of Sleep, Lewis expertly leads an entertaining and informative scientific exploration of those many hours we spend twitching and drooling in bed.