You were invited to spend the night at your best friend's house last weekend. "We'll watch TV, eat pizza and stay up all night playing with my videos," your friend said.
You were excited about staying over at your friend's house. But when the big night came, you both fell sound asleep around 11 p.m. - even though there was a good movie on TV. The next morning, you wondered why your body fell asleep even though you really wanted to stay up.The answer has to do with a "clock" inside you that researchers are still working to understand. That clock makes you want to fall asleep at night on a regular schedule. Sleep researchers say that people feel and think best when they obey this internal clock.
Human beings, like other animals, operate on regular schedules. These schedules are called "circadian rhythms." In Latin, "circa" means "around" and "diem" means "day." Our circadian rhythms operate on a 24-hour schedule - around a day. They influence when you go to sleep and when you wake up. When your internal clock says "sleep," it's hard to resist. You can fall asleep right in the middle of doing something that you enjoy - like watching a late-night movie with your best friend.
We can interfere with our circadian rhythms so that we wake up in time to catch the school bus or get to the airport for a trip. We use alarm clocks to wake us up, even if we're not really ready to get up yet. But when we mess up our circadian rhythm too much, we pay a price for it: tiredness. It may not seem serious to be sleepy when you should be alert. But it can make a big difference if you're driving a car or flying an airplane, taking a test or trying to win a big basketball game.
Once your internal clock has sent you off to sleep, your body undergoes changes. At first, you fall deeply asleep. If someone measured your brain waves - electrical signals that your central nervous system produces - you'd see that they change. After this first stage, another change happens. Someone watching you sleep would notice that your eyes start moving, although they stay closed. You look as if you're watching a tennis game that's being projected on the inside of your eyelids.
Now you're in the REM stage of sleep. REM stands for "rapid eye movement." Your body may be still, but your brain is busy. During REM, blood flow in your brain nearly doubles. Your breathing changes from deep and even to shallow and fast. Your heartbeat changes, too. Researchers believe that people have vivid dreams while they're in the REM stage of sleep. During the night, your body goes through cycles of REM and non-REM sleep. Kids spend about a quarter of their sleep time in the REM stage.
People seem to function best when they experience both REM and non-REM sleep during the night.
During your lifetime, your need for sleep changes. When you were first born, you slept as many as 18 hours out of 24. By the time you were 4, you slept about 10 to 12 hours each night. If you're between 10 and 12 years old now, you probably sleep somewhere between 9 and 10 hours a night and then feel alert all day long. When you're a teen-ager, your sleep patterns will change. You may sleep only about 7 1/2 hours a night, and you may start finding it more difficult to get out of bed in the morning.
A good night's sleep is something most kids take for granted. But some children do have problems, including sleepwalking or talking during sleep, having nightmares or snoring. But insomnia, the inability to fall asleep, is rare in kids. You may have an occasional night when you just can't seem to get to sleep - like Christmas eve or the night before a`big math test - but most of the time school-age kids will fall asleep almost as soon as their heads hit the pillow.
You may have heard that some people try counting sheep to put themselves to sleep. This isn't such a bad idea. Repetition helps set your internal clock to send you off to dreamland. In fact, sleep researchers say that the best way to get restful sleep every night is a bedtime ritual, which seems to help your body settle down and respond to the ticking of its internal clock. Your ritual may be brushing your teeth, plumping your pillow up a certain way and reading one chapter of a book.
Many kids like to have their parents come and tuck them in before they turn the lights out. The trick is to do the same thing at about the same time every night.
Sleep well.
-TIPS FOR PARENTS:
Here are some rules for what sleep expert Peter Hauri of Dartmouth Medical School in New Hampshire calls "sleep hygiene." These guidelines apply to children and adults.
1. Sleep as much as needed to feel refreshed during the following day, but not more. Staying in bed too long seems related to fragmented, shallow sleep.
2. A regular wake-up time strengthens your circadian cycle and eventually leads to a regular time of sleep onset.
3. A moderate amount of daily exercise deepens sleep.
4. Feeling angry and frustrated about not being able to get to sleep does not help. If you can't sleep, turn on the light and do something different.
5. Caffeine in the evening disturbs sleep, even in those who feel it does not (this goes for colas as well as coffee or tea).
-Do you wonder about your body, your feelings or how things work in the world around you? Send your questions to Catherine O'Neill, HOW & WHY, Universal Press Syndicate, 4900 Main St., Kansas City, Mo. 64112.