At first blush, the schedules at most Washington area high schools seem to defy logic. Despite mounds of research suggesting that adolescents require extra sleep, high school students generally wake before dawn and start classes earlier than anyone else.

But changing those schedules is not as easy as it sounds, as members of one Maryland school board learned yesterday.

The Anne Arundel County school board is the latest in the Washington region to study later starting times for high schools. Classes begin at 7:17 a.m. in Anne Arundel high schools, the earliest in Maryland.

"My children go out of the door as zombies," said Eileen Powers, an Annapolis lawyer and parent, addressing the school board yesterday afternoon. "I know that they are not performing to the best of their abilities because they are exhausted."

High school starting times have crept ever earlier over the years, mostly to save money. Faced with expanding enrollments and increasingly complex academic programs, school systems have adopted staggered bus schedules, allowing each bus to run two or three routes a day. High schools are assigned the earliest starting times because they have the most extensive after-school programs and because parents don't want younger children standing at bus stops in the dark.

In Fairfax and Montgomery counties, the largest school systems in the Washington area, high schools start before 7:30 a.m. Both systems have discussed later starting times, but the talk has not led to action.

Serious discussions about changing school hours become ensnared in conflict and competing interests. Coaches typically don't want practice times and game schedules to be disrupted. After-school employers don't want to lose workers. Parents fear complications to their daily drop-off and pickup schedules. And any attempt to simplify the schedule -- say, by having every school open and close at the same time -- becomes a question of spiraling expense.

"Unfortunately, transportation literally drives our system because we are so big and have so many miles," said Kaye Kory, a Fairfax School Board member who has led an effort to reconsider starting times.

Despite the logistical obstacles, most school systems around Washington have discussed later hours for their high schools. The talk reflects a growing recognition that early hours are bad for high school students, who have particular sleep needs. A growing body of research suggests that adolescents require more sleep than adults and that they function best when allowed to sleep until 8 or 9 in the morning.

In December 2000, after a year of meetings, surveys and study, Arlington schools became the first in the region to successfully establish a later starting time for high schools. The School Board moved the start from 7:30 a.m. to 8:15 a.m., chiefly by adjusting the hours of middle and elementary schools. The Alexandria system later followed suit.

While students and teachers in Arlington high schools applauded the new schedule, there was grumbling in the middle schools, which ended up with the earliest start, 7:50 a.m. And while test scores are rising in the high schools, Superintendent Robert G. Smith can't say whether that's because of the new starting time or any of a dozen other factors.

"We overcame a number of logistical barriers to pull it off," Smith said. "There have been issues -- with matching athletic schedules, and those kinds of events, with schools that don't have the same ending time. But we've worked through it."

In Anne Arundel yesterday, the school board reviewed three options. One is to delay the opening and closing times for all schools by 15 minutes, which would cause little harm but provide little relief. Another is to place high schools at the end of the bus schedule, with classes running from 9:30 a.m. to 4:10 p.m., cutting into after-school programs and jobs. A third is to adopt some semblance of the Arlington model, at a potential cost of $3 million to $4 million a year.

Parents at individual Anne Arundel schools have talked about later starting times for years. The issue divides both teachers and parents.

A few months ago, the chairman of the school board's Citizen Advisory Committee, Sam Georgiou, surveyed his membership about delaying starting times by 15 minutes, the simplest option under review. Twenty-one schools said yes and 28 said no, among the parent leaders who responded. Most respondents said they liked the idea of changing school hours -- but not at their school.

"We live in a society," Georgiou said, "where convenience and lifestyle play a big role in dictating how our public schools are operated."