Michelle Healy

USA TODAY

Let them sleep!

That's the message from the nation's largest pediatrician group, which, in a new policy statement, says delaying the start of high school and middle school classes to 8:30 a.m. or later is "an effective countermeasure to chronic sleep loss" and the "epidemic" of delayed, insufficient, and erratic sleep patterns among the nation's teens.

Multiple factors, "including biological changes in sleep associated with puberty, lifestyle choices, and academic demands," negatively impact teens' ability to get enough sleep, and pushing back school start times is key to helping them achieve optimal levels of sleep – 8½ to 9½ hours a night, says the American Academy of Pediatrics statement, released Monday and published online in Pediatrics.

Just 1 in 5 adolescents get nine hours of sleep on school nights, and 45% sleep less than eight hours, according to a 2006 poll by the National Sleep Foundation (NSF).

"As adolescents go up in grade, they're less likely with each passing year to get anything resembling sufficient sleep," says Judith Owens, director of sleep medicine at Children's National Medical Center in Washington, D.C., and lead author of the AAP statement. "By the time they're high school seniors, the NSF data showed they were getting less than seven hours of sleep on average."

Chronic sleep loss in children and adolescents "can, without hyperbole, really be called a public health crisis," Owens says.

Among the consequences of insufficient sleep for teens, according to the statement:

Increased risk for obesity, stroke and type 2 diabetes; higher rates of automobile accidents; and lower levels of physical activity.

Increased risk for anxiety and depression; increased risk-taking behaviors; impaired interpretation of social/emotional cues, decreased motivation and increased vulnerability to stress.

Lower academic achievement, poor school attendance; increased dropout rates; and impairments in attention, memory, organization and time management.

Napping, extending sleep on weekends and caffeine consumption can temporarily counteract sleepiness, but they do not restore optimal alertness and are not a substitute for regular, sufficient sleep, the AAP says.

Delaying school start time is a necessary step, but not the only step needed to help adolescents get enough sleep, Owens says. "Other competing priorities in most teenagers' lives are also components of this problem," she says, including homework, after-school jobs, extracurricular activities and electronic media use. Computers and television screens, she adds, "produce enough light to suppress melatonin levels and make it more difficult to fall asleep."

"The bottom line is if school starts at 7:20 there is no way for the average adolescent to get the 8½ to 9½ hours of sleep they need," Owens says

Research on student performance in schools that have reset the start clock, including Minneapolis Public Schools, "shows benefits across the board," says Kyla Wahlstrom, director of the Center for Applied Research and Education Improvement at the University of Minnesota.

"We've found statistically significant evidence that attendance is improved, tardiness is decreased and academic performance on core subjects, English, math, social studies and science, is improved. And now we have evidence that on national standardized tests such as the ACT, there's improvement there, too," Wahlstrom says.

Obstacles commonly cited to changing school start schedules, include curtailed time for athletic practices and games, reduced after-school employment hours for students and significant impact on bus scheduling and other transportation arrangements, she says, adding, "This is a major policy change that schools have to grapple with if they want to embrace the research about what we know about teens."

According to U.S. Department of Education statistics approximately 43% of the more than 18,000 public high schools in the U.S. have a start time before 8 a.m.; just 15% started at 8:30 a.m. or later.

In some school districts that transport students great distances, buses are picking up students as early as 5:45 a.m., "so there's also a safety element" to early start times, says Terra Ziporyn Snider, executive director of the advocacy group Start School Later.

Other major health organizations, including the American Medical Association and the Centers for Disease Control and Prevention, have all highlighted insufficient sleep in adolescents as a serious health risk, as has U.S. Education Secretary Arne Duncan, Snider says.

"What's unique about the American Academy of Pediatrics' statement is that it's very specific," she says. "It says very clearly that high school and middle schools should not start before 8:30 a.m. for the sake of the health and sleep of our children. They draw the red line."