That's the question many have asked over the years, and it looks like we are getting some answers.
What the Doctors Order....
Delaying the start of the school day until at least 8:30 a.m. would help curb their lack of sleep, which has been linked with poor health, bad grades, car crashes and other problems, the American Academy of Pediatrics says in a new policy.
The influential group says teens are especially at risk; for them, "chronic sleep loss has increasingly become the norm."
Studies have found that most U.S. students in middle school and high school don't get the recommended amount of sleep - 8 1/2 to 9 1/2 hours on school nights; and that most high school seniors get an average of less than seven hours.
More than 40 percent of the nation's public high schools start classes before 8 a.m., according to government data cited in the policy. And even when the buzzer rings at 8 a.m., school bus pickup times typically mean kids have to get up before dawn if they want that ride.
"The issue is really cost," said Kristen Amundson, executive director of the National Association of State Boards of Education.
School buses often make multiple runs each morning for older and younger students. Adding bus drivers and rerouting buses is one of the biggest financial obstacles to later start times, Amundson said. The roughly 80 school districts that have adopted later times tend to be smaller, she said.
After-school sports are another often-cited obstacle because a later dismissal delays practices and games. The shift may also cut into time for homework and after-school jobs, Amundson said.
The policy, aimed at middle schools and high schools, was published online Monday in the journal Pediatrics.
Evidence on potential dangers for teens who get too little sleep is "extremely compelling" and includes depression, suicidal thoughts, obesity, poor performance in school and on standardized tests and car accidents from drowsy driving, said Dr. Judith Owens, the policy's lead author and director of sleep medicine at Children's National Medical Center in Washington, D.C.
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The policy cites studies showing that delaying start times can lead to more nighttime sleep and improve students' motivation in class and mood. Whether there are broader, long-term benefits requires more research, the policy says.
"This is a mechanism through which schools can really have a dramatic, positive impact for their students," Owens said.
Dr. Mary Carskadon director of Chronobiology and Sleep Research at Brown University. She knows how the plea to start school later sounds, but that doesn't change the science.
"It's not just a behavior that teens manifest, which I think people assume 'oh they're lazy, they just want to sleep late,'" Carskadon said.
"In fact, there's some biology behind that. As kids pass through adolescence, their rhythms show a pattern that's pushing later."
Ann Gallagher is an executive member of the organization Start School Later, tying to change public schools' opinions of start time.
"The medical literature, the AMA, the CDC, the World Health Organization clearly state that our teenagers need on average nine hours of sleep," Gallagher said.
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Ann Gallagher, Start School Later.com
"With a school start time of 7:00 or 7:25 in the morning, and we know that the fall asleep time is between 10:00 and 11:00 at night, there is no way to get nine hours of sleep,." she says.
Both Carskadon and Gallagher say that the early start time of high schools interferes with this biological clock, causing students to suffer in their studies.
Can starting school later improve student performance? The Minnesota study says yes, and in more ways than one.
"In one of the districts (where school started later) they showed clear evidence of a reduction in automobile crashes in teenage drivers," Carskadon said
"In a couple of the districts they did show improvement in performance and standardized testing scores. So this is now adding to the growing amount of evidence that indeed the students will sleep more (if school started later), and it would have a significant impact." Carskadon said
Cheektowaga Schools Superintendent Dennis Kane says it's not as simple as it sounds.
"It's one of those things we know is best, but there are just a number of other things that prevent you from doing it," Kane said.
"Very basically, the sun eventually goes down. That effects after school activities." With many activities going late as it is, Kane says there's only so far you can push the start of the day back.
But how later should school start? Carskadon says that even just one hour can make a big difference.
"That hour is huge. That hour is five hours over the course of a week, 10 hours over two weeks, it adds up."