While there are several articles and studies for adults to read about why sleep is beneficial, there may not be as much literature directed at kids.
Sleepforkids.org is one option to show kids that learning about sleep can be informative and entertaining. This sleep site explains why we sleep and how sleep works in terms that kids will understand. It also offers explanations on why you can’t sleep, dreams, and the relationship between yourself and sleep. To top it all off, this website provides an activity page, games and puzzles, and a booklet that also helps teach children about sleep.