In America, most people don't get enough sleep. Children aged 5 to 12 are advised to sleep 10 to 11 hours every night, but most of them can't sleep that long. A study found that about 41 million American workers got less than six hours of sleep every night. Scientists worry that parents are passing their bad sleeping habits down to their children. In the study, Reut Gruber and some other scientists either added or reduced on hour of sleep for healthy children aged 7 to 11. They watched the children for five nights. They wanted to know if the amount of sleep can affect a child's behavior. Before the study began, students were asked to sleep the same amount of hours as usual. Their teachers were asked to record their behavior. After five nights of the records, scientists found that those who slept one hour less behaved worse than those who slept one hour more. Students with less sleep were more likely to feel sad and had more problems paying attention. The scientists chose to study children in their homes instead of in a laboratory, because they wanted to find out how everyday changes might affect children's behavior at school. "In the study, nobody became a talent, and nobody became crazy. But small changes in children can really make a big difference," says Gruber. Scientists did the new study in order to know  _  .
why children can't get enough sleep how long children should sleep every night what children like to do before they go to sleep if the amount of sleep can affect a child's behavior