In a slim, colorful volume, this 21st Century Junior Library/Your Healthy Body title offers a simple introduction to sleep and its importance to one’s health. The content touches on sleep’s physical and mental benefits, including better coordination, concentration, and mood; sleep-cycle stages; and ways to better sleep—and what can disrupt it, like TV’s lights and sound. Spreads feature pages of brief text, in well-spaced, larger font, facing stock photos, with side-fact cutlines—although the images, often of kids sleeping, are more accompaniment than illustrative. Occasional interspersed reader-addressed queries, in smaller text, invite additional thought or provide ideas for research (with adult help) to discover, for example, the impact of exercising or eating “sugary foods” before bedtime. An accessible overview of sleep’s basic elements.