The body may not be very active during sleep, but the mind has an important job to do. Sleep is a crucial function for all complex animals, yet there are still many questions to be explored. Why do we sleep? Why might it help our memory? Why do we dream? This fascinating book dives right into the world of sleep, focusing on the brain's functions and role in making sure healthy sleep is achieved. Young readers gain access to complex biology topics with age-appropriate vocabulary. This text teaches young readers that sleep is just as important for the body as it is cool to study.