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Bedtime used to be a problem for Eve R. Worries about school and friendship issues often kept her from falling asleep. That would make school tough the next day. “I didn’t want to apply myself,” recalls Eve. “Every class was hard to get through.” She felt fidgety, and her family members complained that she was moody. That was a few years ago. These days, a relaxation technique she learned in health class helps Eve, a 10th grader in Mountain View, Calif., fall asleep more easily. So does throwing a towel over the glowing face of her alarm clock.

Whether it’s because of busy schedules, heavy homework loads, or late-night computer games, many kids are getting far less than the 9.25 hours of sleep they need every day. The National Sleep Foundation (NSF) says six out of 10 middle school students sleep fewer than 9 hours each night. And two in 10 students get fewer than 8 hours of sleep daily.

Why Sleep Matters

Sometimes, not getting enough sleep is hard to avoid. The challenge is to not let droopy eyelids and yawning your way through morning classes become a way of life. "Everyone has nights when they don't get enough sleep. Situations come up, like worrying about a test the next day and Friday night football games," says Dr. Daniel G. Glaze, clinic chief of the Texas Children's Sleep Center at Texas Children's Hospital in Houston.

But, he adds, if you often skimp on sleep, you can harm your health, moods, schoolwork, and sports performance.

“We all need sleep to restore us,” for both our bodies and our minds, explains Dr. Helene A. Emsellem. She specializes in teen sleep disorders at the Center for Sleep & Wake Disorders in Chevy Chase, Md. When you don’t get enough sleep, she says, it is easy to lose focus and hard to concentrate. Your reaction time slows too.

Good for Body and Mind

Getting a good night's sleep can boost your learning power. While you're snoozing, your brain is busy. During sleep, the brain processes information you received during the day, says teen sleep expert Mary A. Carskadon of Brown University in Providence, R.I. "A good night's sleep solidifies the learning," she says.

A healthy body is one that is well rested. A lack of sleep can affect your growth and recovery from an injury or infection. That’s because growth and repair of cells and tissues takes place during deep sleep.

Deep sleep is also when the immune system is busy strengthening itself and fighting infection in your body. So a lack of sleep can make you more likely to catch colds or the flu. “It also makes it harder to shake a cold once it settles in your system,” says Glaze.

Studies also show that a lack of sleep affects hormones that tell the body whether it is hungry. That could result in overeating and gaining weight—and extra weight can increase the risk for medical problems.

A good night's sleep is your ticket to good health. "If you can improve your sleep," says Glaze, "you can improve so many other aspects of your life."

Sleep Tips

Ready to change your sleep habits and improve your health? These sleep-smart tips will help you get the z's you need.

Commit to more sleep. If you have to be up early, you may need to change your habits so you get plenty of shut-eye. Wind down by starting a new bedtime routine. Take a warm shower, dim the lights, read, lay out clothes for the next day, or listen to soothing music at a low volume.

Turn off the electronics earlier. For a good night's sleep, power down cell phones, games, computers, and TVs at least 30 minutes before bedtime.

Check your caffeine intake. Soft drinks, coffee, tea, and energy drinks you gulp down to stay alert during the day can haunt you at night. Try to minimize (or avoid) caffeine after noon.

Minimize sleeping in on weekends. It's tempting to use weekends to catch up on sleep. But that will backfire if you sleep until noon on Sunday. You'll be too awake to fall asleep at a reasonable time Sunday night and will start the new week with a sleep deficit. Allow yourself no more than two hours of extra sleep on weekends.

Worry before you hit the pillow. Try talking about your worries with someone earlier in the evening, or write them down in a journal. Deep breathing and stress reducing techniques can be relaxing too. Before Eve goes to bed, she imagines a long hallway with several doors. “Then one by one,” she explains, “I put my worries behind the doors and shut them out for the night.”

Think About It:

What are some activities you like to do that could be affected if you don't get enough sleep?

–A version of this article appeared in Current Health 1, October 2009