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.
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.
Many administrators support the idea but haven't resolved the challenges, said Amundson. She said the pediatricians' new policy likely will have some influence.
Parents seeking a change "will come now armed with this report," Amundson said.
Amundson is a former Virginia legislator and teacher who also served on the school board of Virginia's Fairfax County, near Washington, D.C. Owens, the policy author, has been working with that board on a proposal to delay start times. A vote is due in October and she's optimistic about its chances.
"This is a mechanism through which schools can really have a dramatic, positive impact for their students," Owens said.
American Academy of Pediatrics: http://www.aap.org