NEW YORK - Quinn Cooney of Mill Creek, Wash., is excited about starting high school in September, but she's not looking forward to waking up at 5:30 a.m. to arrive on time. Classes for ninth-graders start at 7:30 a.m., 45 minutes earlier than they did in middle school.

"I think it is going to be harder to get up," said Quinn, 13. "I do think it is better to start early so that we can be finished early and do things after school, but I am worried that if I have a boring class for my first period that it will be hard to stay awake."

Decades of sleep research have confirmed what parents know: It's hard for teenagers to wake up early. Some high schools have adopted late starts around 8:30 a.m. to improve attendance and performance. But other districts say it's too complicated to shift schedules because of logistics involving buses and after-school activities.

About 40 percent of U.S. public high schools open before 8 a.m., according to the U.S. Department of Education's National Center for Education Statistics, with just 15 percent starting 8:30 a.m. or later.

In districts where early starts are necessary because the same bus does multiple runs for high school, middle school and elementary students, teens often get the early shift.

Megan Kuhfeld, a graduate student at UCLA who studies the subject, surveyed about 35 districts that switched to later starts and found most were glad they'd made the switch. Not only did students benefit for the most part, but "the things people had feared - how transportation would be affected, how sports would be affected - became the new normal and people adjusted," she said.

Advocates say several studies show the benefits of late starts outweigh the drawbacks.

The local angle

While starting times vary across Tucson schools, several local districts say bell schedules are not put together with students' sleep schedules in mind. Rather, the focus tends to be on busing - efficiency in routing and the number of buses and drivers available.

In Tucson's largest school district, TUSD, high school classes generally start around 8 a.m. Sunnyside Unified School District classes begin about an hour earlier except on Wednesdays, which are collaboration days for teachers, resulting in a 9:30 start time. Amphitheater high schools kick off around 7 a.m.

While Sunnyside's leadership has discussed the possibility of later start times, there are no plans to do so, said district spokeswoman Mary Veres.

There have been no discussions of altering schedules in the Vail School District, where high schools start between 7:40 and 8:40 a.m.

"We're a rural district," said Vail spokeswoman Natalie Luna Rose. "We have many stops and we have a smaller fleet. It's just easiest to make arrangements based on bus schedules."