Parents in Montgomery County have started a movement to start high school classes later, pointing to research linking extra sleep to the healthy development of teens.

As of Wednesday afternoon, an online petition to move the first bell back from 7:25 a.m. to 8:15 a.m. or later had gathered 2,350 signatures, virtually all from county residents. Mandi Mader, the mother of a sophomore at Walter Johnson High and a sixth-grader at Tilden Middle, created the petition as the first act of the Montgomery County chapter of national advocacy group Start School Later.

Mader, a clinical social worker who treats adolescents, formed the chapter in late September with other Walter Johnson parents. "I've been very frustrated with some of the adolescents I've worked with being anxious, stressed, even suicidal and cutting, and they're Montgomery County high school students who need to get healthy and need more sleep," she said.

Carol Liu, the mother of a Tilden sixth-grader and an eighth-grader, said she signed the petition because she finds the early start time at odds with her efforts to teach her children the importance of a healthy sleep cycle. Liu said her children don't get enough sleep as middle-schoolers and is concerned about what will happen when her oldest moves to high school next year.

"She's a kid who gets good grades, straight As, but she's told me she's almost fallen asleep in class many times," Liu said. "She's not going to live up to her potential as a student if I can't get her the recommended hours of sleep."

Studies show that teenagers who get nine hours of sleep have better attendance records and are less likely to become depressed than their peers, with scientists emphasizing adolescence as a key time for brain development.

Arlington County moved back the start time for its high schools by 45 minutes to 8:15 a.m. in 2001, relegating its elementary and middle schools to earlier bell schedules. Loudoun County has done the same.

But the decision isn't so simple: School buses often serve multiple schools on a tight schedule, and later dismissals affect after-school activities. The Fairfax County School Board has studied the issue eight times in the last 24 years but has yet to implement any changes.

Dana Tofig, a spokesman for Montgomery's schools, said the school board is not considering a later bell schedule at this time: "Any such changes would certainly have a dramatic impact on all students, due to bus schedules, after-school activities, as well as students who have jobs and other commitments outside of school."

Mader said she had emailed the chiefs of staff for both the school board and for Superintendent Joshua Starr on Tuesday but had not received a reply as of Wednesday afternoon.