Sleep
(Imagine This!)

PreS-Gr 3--Part of the "Imagine This!" series, this title delves into how and why sleep is a necessary function and what various animals do during their slumber. The main text discusses sleep cycles, how long different species sleep, and how some animals only sleep with half their brain at a time. Additional details, such as the lack of REM sleep in dolphins and whales, are in smaller font and tucked into the illustrations rather than set aside in text boxes. Illustrations show a variety of animals resting--puppies snuggled on a blanket, sperm whales "floating tail-down," bats hanging from tree branches. The final spread is a baby in a crib accompanied by an explanation of how the amount of sleep needed changes as humans grow. Back matter includes an author's note, glossary, and suggested books. Readers will be surprised to learn that animals as varied as jellyfish and elephants sleep in very different ways. This book strikes a nice balance between explaining the human need for sleep and how our sleep cycles compare to those of animals around the world. VERDICT A solid introduction to the biological function of sleep; sure to please budding biologists and those who keep asking "Why do I have to go to bed?"--Suzanne Costner