We all do it． We all need it． Most of us need to do it for seven to nine hours a night， It is of course sleep． Many scientists believe that an average adult should get eight hours sleep per night． However， some people can live without feeling sleepy after as little as six hours of sleep． Yet， other people need about ten hours a night． Newborn babies usually sleep between 14 to 17 hours a day． Usually they only stay awake for one to three hours．

    Do you take a nap in the day？ Some adults and children need to nap． This just depends on the person． One thing scientists have learned is that man is the only mammal that stops himself from going to sleep． This can be bad for our bodies in many ways． Scientists believe not sleeping enough can make us eat more and put on weight． That's right! A hormone called leptin falls when we don't sleep enough and this makes us hungrier． Hopefully you are a good sleeper and get a good night's rest tonight!

average 平均   mammal 哺乳动物    hormone 荷尔蒙

（1）Most people need to sleep for　　 per night．

A． 6 hours

B． 8 hours．

C． 10 hours．

（2）What does the underlined word "nap" mean in Chinese？　　

A． 打盹

B． 深睡眠

C． 加餐

（3）What can we tell according to the passage？　　

A． Enough sleep can make us eat more．

B． A dog can stop itself from going to sleep．

C．A hormone goes down when we haven't enough sleep．