A、They do not perform well at school. B、they look more tired. C、They look very energetic. D、They are easily angry. C讲话人提到疲劳的孩子与成

Now, health officials have begun a campaign to urge children to get enough sleep. The officials say children need at least nine hours of sleep every night.(33)They say research shows that children who get this much sleep perform better in school, suffer fewer accidents and are less likely to become too fat. Studies show that lack of sleep causes tiredness and problems with clear thinking. People who do not get enough sleep become angry easily and have trouble controlling their emotions. Among children, problems that result from lack of sleep often are mistaken for more serious disorders.(34)Unlike adults, tired children seem to have endless energy. Some doctors mistakenly identify this as hyperactivity.
    Experts say many American teenagers are not getting enough sleep. Many high school students in the United States start school very early in the morning. A University of Minnesota study found that attendance at the high schools improved after the starting time was changed. However, the later start did not greatly affect the performance of the students.
    The American Academy of Pediatrics represents doctors who treat children. It notes that many sleep disorders first develop in childhood. It says doctors often do not identify the disorder until years later.(35)The group has agreed to join in a study with the National Center on Sleep Disorders Research. During the next five years, they plan to examine sleep problems in very young and older children. They also will develop guides for doctors to use when testing for sleep problems. And they will provide educational materials about the importance of healthy sleep .
33. Q: According to the studies, what might happen to children who sleep nine hours every night?
34. Q: What might make doctors mistakenly diagnose children’s lack of sleep?
35. Q: What do we know about the American Academy of Pediatrics?