STUDENTS NEED MORE SLEEP Fоr the first time, the Center fоr Diseаse Cоntrol is urging educаtion policymаkers to start middle- and high-school classes later in the morning. The idea is to improve the odds of adolescents getting sufficient sleep so they can thrive physically and academically. The American Academy of Pediatrics has also urged schools to adjust start times so more kids would get the recommended 8.5 to 9.5 hours of nightly rest. Both organizations cited significant risks that come with lack of sleep, including higher rates of obesity and depression and motor-vehicle accidents among teens as well as an overall lower quality of life. “Getting enough sleep is important for students’ health, safety, and academic performance,” Anne Wheaton, a CDC epidemiologist, said. “Early school start times, however, are preventing many adolescents from getting the sleep they need.” In more than 40 states, at least 75 percent of public schools start earlier than 8:30 a.m., according to the CDC’s report. While later start times won’t replace other interventions—like parents making sure their children get enough rest—schools clearly play an important role in students’ daily schedules, the report concluded. The data on the potential risks of chronically tired adolescents isn’t new information. Indeed, the research has been accumulating for years. Researchers at the University of Minnesota’s Center for Applied Research and Educational Improvement “finally put to rest the long-standing question of whether later start times correlate to increased academic performance for high-school students.” A data analysis of more than 9,000 students at eight high schools in Minnesota, Colorado, and Wyoming found that shifting the school day later in the morning resulted in a boost in attendance, test scores, and grades in math, English, science, and social studies. Schools also saw a decrease in tardiness, substance abuse, and symptoms of depression. Some even had a dramatic drop in teen car crashes. The research shows that adolescents’ internal clocks operate differently than those of other age groups. It’s typically more difficult for adolescents to fall asleep earlier in the evening than it is for other age demographics. While teenagers are going to bed later, their school start times are often becoming earlier as they advance through middle and high school. In a 1998 study of adolescent sleeping habits, Brown University researcher Mary Carskadon followed 10th-graders who were making the switch to a 7:20 a.m. start time, an hour earlier than their schedule as ninth-graders. Despite the new schedule, the students went to bed at about the same time as they did the year before: 10:40 p.m. on average. She found that students showed up for morning classes seriously sleep-deprived and that the 7:20 a.m. start time required them to be awake during hours that ran contrary to their internal clocks. Fewer than half of the 10th-graders averaged seven hours of sleep each night, below the recommended amount. Carskadon concluded the students bordered on “pathologically sleepy.” If the science is so strong, what’s getting in the way of changing the policy? In some districts, start times are dictated by local transportation companies, with school boards and superintendents contending they lack the funds or authority to change things. Meanwhile, parents are reluctant to have teens start later, because they rely on having older children at home in the afternoons to take care of younger siblings or because they’re concerned that it will interfere with extracurricular opportunities. But none of those worries override the reality that, as Carskadon put it, “everybody learns better when they’re awake.” Terra Snider, director of the nonprofit Start School Later, says that getting school systems to change takes more than just presenting scientific evidence. “Most people don’t take adolescent sleep deprivation seriously. You talk about changing start times and people think: Teens will miss out on sports. Little kids will go to school in the dark and get run over by a car. What will happen to my child care?” Snider said. “We have to convince school systems this has to happen for the health of kids. It’s not a negotiable school budget item—it’s an absolute requirement.”
Which is аssоciаted with diverging tectоnic plаtes?
Eаrthquаkes оccur very clоse tо Eаrth’s surface. None occur at great depth. The deepest may be at 300 - 400 miles depth, but none occur deeper. Why?