Going to sleep may seem pretty boring compared with all the fun things you do while you are awake.
But there's a lot going on in your mind and body while you are sleeping.
      Sleep, in fact, is as important to your survival as eating and drinking. Sleep improves your mood,
makes you a better athlete, and helps you remember and understand what you learned during the day.
      During sleep, your temperature drops. Your heart beats slowly. A chemical that controls growth,
which is called a hormone (荷尔蒙), moves into your bloodstream. Scientists think that sleep brings back
energy and improves your immune (免疫) system. We know what happens while we're asleep because
scientists study volunteers who sleep in laboratories. The sleepers are connected with machines that
measure brain waves, eye movements and muscle activities.
      Sleep is like a school day: it's divided into different stages (阶段). When you are awake, your brain
waves fire rapidly (迅速地). As you begin to relax and drift into the first stage of sleep, your brain produces
slower-moving waves and you lose awareness (意识) of your surroundings. As you fall into deeper sleep,
your body repairs itself from the normal wear and tear of daily life. Then, as you begin to drift back up to
a lighter sleep, your mind becomes more alert (警觉的), and your dreams begin. You are in REM sleep.
      REM is the name for the rapid eye movement that happens while you are dreaming. During REM sleep,
your eyes move back and forth behind your lids, as though you were watching a movie. During other
stages, you might move in bed, but during REM sleep you're not making any movement. That's probably
because if you could move, your body would act out your dreams. As you get close to morning, you
spend more time in REM than in deep sleep, so you dream more. Researchers know that during REM sleep
the part of the brain that deals with learning and thinking is very active.
     Getting too little sleep can affect your personality. Experts recommend that children get at least nine
hours'sleep a night.

1. Sleep has many advantages except _______.

A. improving your mood
B. making you strong
C. helping you study
D. practising your eyes

2. During your sleep, _______.
    ① your body repairs itself from the normal wear and tear of daily life
    ② your brain produces slower-moving waves
    ③ your dream begins
    ④ you lose awareness of surroundings Choose the right order:

A. ①③②④
B. ②④①③
C. ④①③②
D. ④③①②

A. Light sleep.
B. Deep sleep.
C. REM sleep.
D. The first two stages of sleep.

4. Which of the following is NOT right?

A. During REM sleep, the whole brain is active.
B. You don't move while you are in REM sleep, dreaming.
C. The closer to morning, the more dreams you have.
D. Hormone has something to do with your growth.

     Do you remember your dreams? Do people have the same dreams? Why do we dream? There are
many questions about dreams. We dream during the REM (rapid eye movement) stage of sleep. We
have about five periods of REM sleep during the night. The first REM cycle (周期) lasts about 10
minutes. As the night goes on, the REM cycle gets longer. By early morning, the REM cycle can last
up to 90 minutes. Usually, it is in this last REM cycle that we remember our dreams.
     Dreams change as people age. People may have several dreams each night. Some are like films
and usually in colour. They come to us over and over again. That may be because the dreamer is
worrying about something and trying to find the answer. Sometimes we wake up with a good feeling
from a dream. But often we can't remember the dreams clearly.
     It is reported that too much dreaming is bad for our health. The more we sleep, the longer we dream.
The mind is hard at work. That is why we may have a long sleep and still feel tired when we wake up?

(     )1. We dream during the REM stage of sleep.                                
(     )2. Children aged eight or nine have the same dreams as people aged thirty.
(     )3. All the dreams are usually in colour like films.                      
(     )4. The longer we dream, the better we sleep.                              
(     )5. The passage above is talking about dreams.                            

     Do you remember your dreams? Do people have the same dream? Why do we dream? There are many
questions about dreams. We dream during the REM (rapid eye movement 眼球快速移动) stage of sleep. We
have about five periods of REM sleep during the night. The first REM cycle (周期) lasts about 10 minutes.
As the night goes on, the REM cycle gets longer. By early morning, the REM cycle can last up to 90 minutes.
Usually it is in this last REM cycle that we remember our dreams.
     Dreams change as people age. People may have several dreams each night. Some are like films and usually
in color. They come to us over and over again. That may be because the dreamer is worrying about something
and trying to find the answer. Sometimes we wake up with a good feeling from a dream. But often we can't
remember the dreams clearly. 
     It is reported that too much dreaming is bad for our health. The more we sleep, the longer we dream. The
mind is hard at work. That is why we may have a long sleep and feel tired when we wake up.

根据短文内容判断下列句子正（T）、误（F）。
(     )1. We dream during the REM stage of sleep.
(     )2. Children aged eight or nine have the same dreams as people aged thirty.
(     )3. All the dreams are usually in color like films.
(     )4. The longer we dream, the better we sleep.
(     )5. Too much dreaming is bad for our health.