You want to stay up late and watch "South Park." Your Mom says you have to be in bed by 9. Who's right?
Well, what time do you have to get up the next morning? If that alarm clock is going to blast you out of bed at dawn, then, sorry--Mom wins. Most kids need about 10 hours of sleep each night, says Dr. Donald Shifrin, a doctor for kids at the University of Washington.
Do the math. If you watch television until midnight, then get up at 6:30 a.m., all you're getting is 6 1/2 hours of sleep. That's not enough. Somewhere between gym class and science, your head's going to hit the desk, and you'll be snoring with your mouth open. To spare your classmates this sight, you've got to get to bed earlier.
When you don't get enough sleep, your energy level is low and you're not going to do your best, academically, athletically or socially. Shifrin says that lack of sleep can also cause behavioral symptoms like hyperactivity, aggressiveness and inability to pay attention. Sleep-deprived kids tend to have lower grades than kids who are well-rested.