This introduction to sleep is a welcome addition to the "Let's-Read-and-Find-Out" series that brings basic science concepts to very young children. It talks about how animals sleep, why people need sleep, and what happens when people don't get the sleep they need. It's nonfiction, but could easily be used as a bedtime story book since the book concludes with descriptions of how to relax and get ready for sleep. While the text is twenty-five years old, the brilliant collage illustrations are brand-spanking new and as refreshing as a good night's sleep. Level 1 in the series.