In addition to studying the natural onset of teen sleep, many have looked into the amount of sleep teens need. The evidence supports the conclusion that teens need more than nine hours of sleep each night. In “Teens Need More Sleep, Experts Say,” a study reports that “almost all high school and college students do not get enough sleep.” Additionally, a work entitled “The Sleep Needs, Patterns and Difficulties of Adolescents: Summary of a Workshop” reports 26 percent of adolescents are getting 6 or fewer hours of sleep each night. With some 29 million teens in the nation, that means more than 5 million are trying to function without sufficient sleep. Along with researchers, many parents believe that the fault lies with the times. The University of California at Berkeley sponsors a website on which parents around the country weigh in on the sleep troubles their teens face. The biggest problem, they say, is the sleep deficit caused by school classes that start as early as 6:20 A. M. In online forums on the topic, parents note that at many schools a single section of a specialty class such as advanced placement is only offered at an early hour. They argue that schools need to start later. In Minnesota, one community embraced the later start in 1996. In the town of Edina, high-school classes no longer start at 7:25 A. M. but instead begin at 8:30 A. M. If a teen’s biological clock kicks in for sleep around 11:00 P. M., a teen who lives in Edina can get almost nine hours of sleep before a rush to the bus. Has the change made any difference in Edina? A year after the change, teachers reported much more positive and interactive first-period classes. They also noted that their sixth-period classes were no longer outperforming the first-period ones. A few more school districts have altered their start times, but there still is no national trend toward later classes. Until school leaders commit to the changes the studies recommend, though, there are positive steps teens may take to improve the amount of sleep they get. First, set a bedtime and stick with it. Next, avoid caffeine, which inhibits restful sleep as many as 12 hours after consumption. Get fresh air and exercise daily. And finally, pay attention to your body. Sleep when you need sleep. Stop over programming yourself. You have a lifetime ahead that depends on the good sleep you can give yourself tonight. Sleep on it. 13 Select the correct answer. Which group is the most likely intended audience of the passage? A. parents B. scientists C. teenagers D. school authorities