UNDER THE MICROSCOPE
Think that sleeping is a snooze? No way! Your brain is as busy when you’re asleep as when you’re awake.
Sleep is divided into five stages. The sleep stages come in cycles. All night, we go through a series of cycles that last about 90 minutes
Stages 1 and 2
Light sleep. In fact, stage 1 sleep is very close to being very relaxed when you’re awake. It’s easier to wake up or be woken up. If you wake up in these phases, you might not even realize you were asleep!
Stages 3 and 4
Deep sleep. Your breathing and heart rate slow down. The deeper the sleep, the better it is for you. It’s hard to wake up from stages 3 and 4. You might feel groggy or not realize what’s going on at first.
REM is short for “Rapid Eye Movement.” This stage is when you dream. If you remember a dream, it’s probably because you were in REM sleep when you woke up. You can tell when someone’s in the stage because their eyes move around, even though they’re closed, like they’re looking at everything in their dream. The brain sends out signals to the rest of your muscles to keep them from acting out your dreams. Sometimes, the signals don’t work. That’s when some people might talk or walk in their sleep. Scientists don’t know yet why that happens.
While you sleep, your brain stores what you learned during the day before. This means that the next day, you can remember what you learned, pay attention and concentrate, and solve problems and think of new ideas.
Your brain also releases hormones that control how you grow. While you sleep, your muscles, bones, and skin heal and grow, and your immune system gears up in case you need to fight off an illness.
The day after you don’t get enough sleep:
- You’ll be sleepy (duh!).
- You might be cranky, moody, or get upset easily.
- You can have trouble concentrating.
- Things that are normally a breeze might be really hard.
- Page last reviewed: May 9, 2015
- Page last updated: May 9, 2015
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