Fairfax County’s school board is formally reopening a long-simmering debate over whether to start high school classes later in the morning so teenage students can get more sleep.

Classes in Fairfax begin as early as 7:20 a.m. and school buses begin picking up students before 6 a.m.

Critics of the current schedule have been pushing for change for nearly a decade, arguing that forcing teenagers to wake up (and function) before dawn runs counter to their natural body clocks and is detrimental to their academic performance and mental and physical health.

“Right now, our schedule makes it virtually impossible for students to get the amount of sleep they need,” said school board member Sandy Evans (Mason). “This is a very important health issue.”

Evans has brought forth a resolution that, if passed, would declare that one of the board’s goals is for high schools to start after 8 a.m. The resolution also would call on Superintendent Jack D. Dale to explore how other school districts — including Arlington and Loudoun counties — have achieved later start times, and would direct Dale to report his findings by June.

The board will vote on the measure on April 12.

The Fairfax board last considered the issue in 2009.

That year, after arguing that adding buses would be too costly — estimates ranged from $4 million to $40 million — the school system devised a no-cost plan to rearrange schedules and bus routes so high schools could start an hour later.

The board rejected the proposal in a 10-2 vote after many students, parents and teachers said the change would have too great an impact on work schedules, child-care arrangements and after-school activities.

Since then, a school board election ushered in six new members who have demonstrated a willingness to reverse decisions made by their predecessors.

“I’m hopeful,” said Evans, who was elected in 2010. “We can start fresh with this board.”

Evans co-founded the advocacy group SLEEP (Start Later for Excellence in Education Proposal) in 2004. Nearly 9,000 people have signed the group’s online petition urging school and county officials to address the issue.

Phyllis Payne, another co-founder of SLEEP, said that although approving the resolution would be a positive step, it wouldn’t actually change anything for sleepy students. “We still have a long way to go in finding the solution that will work in Fairfax,” she said. “But I completely believe that we can find that solution.”

The school board heard testimony on the issue last week from several members of the public.

The speakers urged the board to adopt the resolution, telling stories about exhausted sons and daughters struggling to meet the demands of school and extracurricular activities.

Roger Cryan, a father of two Fairfax students, argued that sports programs wouldn’t be hurt by shifting the school day, as some people worry.

His own analysis, Cryan said, showed that “Loudoun County football teams, whose well-rested players start school at 9, were 10-2 against Fairfax County schools last fall.”