Why do we sleep anyway? That’s 9 hours I could be playing video games, practicing my free-throw, or even studying—what a waste!

No way is sleep a waste! Sleep is an important a part of your health and energy—it ranks right up there with diet and exercise. Sleep gives you the energy to play video games and basketball, and to study. Even if you could study for 9 hours straight without getting tired, you’ll remember what you studied more if you sleep after studying. While you sleep, your body stores memories. And not sleeping enough can make you clumsy—that’s no good while you’re on the court. While you sleep, your brain releases the hormones that control your growth. If you don’t sleep enough, you may be tired, cranky, klutzy, and forgetful.

While scientists are a little baffled about why all this recharging can happen only when we sleep, they all agree that we do need to sleep.