Today’s Wonder of the Day was inspired by Tara from Plain, WI. Tara Wonders, “How does your body shut down for sleep?” Thanks for WONDERing with us, Tara!

Hey you! Wake up! Yes, we're talking to you. Now is NOT the time to sleep. It's time to WONDER. In a little bit, it'll be time to put what you learned into action. THEN it'll be time to sleep!

So what are we talking about today? You guessed it! Sleep. Sounds boring, right? After all, not much happens during sleep. Your body just kind of shuts down, doesn't it? Well, read on and you might be surprised to find out all that does happen when you sleep.

Your parents and teachers probably tell you regularly how important sleep is. Most children would prefer to stay up as late as possible, though. It's just no fun to go to bed when there are still books to be read, movies to be watched, and games to be played.

But remember what it feels like when the morning comes and your bedroom light is switched on. Those dreaded words — “Time to get up!" — reach your ears and you would give just about anything for a few more hours of sleep.

Adults who work hard all day and then take care of their kids all evening understand the value of a good night's sleep. As you get older, you'll understand, too. Sleep is very important and learning that right now can help you in so many ways. Those tests and big games? They're all a lot easier if your body is well rested.

The human body is an amazing machine. But it needs to be rejuvenated by sleep each and every day. Sometimes a little sleep in the middle of the day in the form of a catnap is even necessary!

Do you enjoy going on vacation? Who doesn't, right? You can think of sleep as a daily mini-vacation for your body. It needs a break from all that walking, thinking, studying, reading, eating, and playing.

So what exactly happens when you sleep? Does your body just shut down? Not at all! You actually go through five stages during sleep, and your brain guides your body along the way, telling it how to sleep.

In the first stage, your muscles relax, your body temperature gets a bit cooler, and your heart beats a bit slower. In the next stage, you fall into a light sleep. At this point, you can still be awakened fairly easily.

As you enter the third stage, your body goes into a deeper sleep, sometimes called slow-wave sleep. Your blood pressure lowers, and your body becomes less sensitive to your environment, such as the air temperature. At this point, it's harder to awaken you.

The fourth stage is an even deeper sleep. In this stage, it's difficult to wake you up. If you are awakened at this stage of sleep, you're likely to be really out of it and confused for a while.

The final stage of sleep is known as REM sleep. REM stands for “rapid eye movement," because that describes what your eyes do behind your eyelids during this stage. During REM sleep, your body's muscles are totally relaxed, but your eyes move back and forth rapidly behind your eyelids. REM sleep is when most dreams occur.

Experts believe your body moves back and forth through sleep stages 2, 3, 4, and REM approximately every 90 minutes until you wake up in the morning. For most kids, that's about four or five times through each stage each night. We bet you had no clue you were sleeping so actively!

Sometimes when you're falling asleep, your body may suddenly jerk and you're back awake for a second. Has that ever happened to you? Why does it happen?

Scientists call those experiences sleep starts or hypnic or myoclonic jerks, and they're not sure exactly why they happen. But they're very common and completely normal. Since they occur before you enter the deeper stages of sleep, some scientists believe they may be the brain's reaction to your body's muscles relaxing. Sometimes your brain may interpret your relaxing muscles as falling and tense your muscles suddenly in response to prevent a fall, resulting in an involuntary body jerk.

Wonder What's Next?

Surfers beware! Tomorrow’s Wonder of the Day features a wave that you won’t want to catch. Find out what happens when the Earth quakes and the oceans roar…