In the minutes before the first bell of the day rings at East Ridge High School in Woodbury, Minn., dozens of students are studying and hanging out in the library.
But there's not a bleary eyed teen in sight -- a remarkable scene for anyone familiar with the early morning zombie-like state of the typical sleepy teenager.
That's because the school day begins at 8:35 a.m.
The state doesn't track school start times, but East Ridge officials here say that's at least an hour later than when most Minnesota high schools begin.
"It's awesome; you get to sleep in more," said 17-year old junior Joseph Koslik, a fan of the late start. "You have time to get to your classes, get some work done beforehand and hang out with friends. It's pretty fun."
A new University of Minnesota study finds high school students who start school later receive better grades and are absent less often. The findings add to a growing body of research that shows teens need more sleep to function well in school.
That has some Minnesota districts considering a later start for high school students. But making such a change, even when backed by solid data, isn't an easy one for school districts.
Four years ago officials in the South Washington School District decided to push back the start time for all of the district's high schools by an hour.
East Ridge High School principal Aaron Harper was on the committee that studied and then implemented the change.
"We're really taking more of a brain-based, biological, educationally sound approach, which is students learn better later in the morning," he said.
The later start time appears to have made a difference in student performance.
When University of Minnesota researchers compared the grades of South Washington high school students before the time change with those after the change, they found that overall grade point averages went up by as much as a quarter of a point in many subjects.
The research is part of a study by the Centers for Disease Control and Prevention to be released later this month. The local data, shared with district officials this week, also found that after the schedule change fewer students were reported absent.
U of M education and sleep researcher Kyla Wahlstrom, who has studied the effect of later start times on high school students for nearly two decades , conducted the research.
"It's awesome; you get to sleep in more... You have time to get to your classes, get some work done beforehand and hang out with friends. It's pretty fun."
Her first study focused on the Edina school district, which pushed back its school day 17 years ago. Since then, she has heard a similar refrain from schools across the country that changed their start times.
"The teachers said 'the kids are different; they're ready for learning,'" she said.
Wahlstrom also cites other benefit. With a later start, students are in a better mood, their behavior improves, they're less likely to be involved in car accidents, and overall they're healthier.
For anyone who thinks that school leaders who approve the change are going soft on students, there is overwhelming evidence that high school students are in need of a delayed start, said Dr. Con Iber, Wahlstrom's fellow researcher at the U of M and director of the sleep program at Fairview Health Services in Minneapolis.
Iber said teenagers need eight to nine hours of sleep a night and are hardwired to stay up later and sleep in later.
"That's not something that's related to their motivation, or their avoidance of adults," he said. "That's biology."
With growing evidence that later school times are best for teenagers, why isn't it something that all Minnesota high schools are doing?
Simply put, tinkering with established school schedules is bound to upset a lot of people.
It's an adjustment that can be gut-wrenching for parents whose lives and work schedules are set around the opening and closing bells of school.
Moving the start of school back, even an hour, means reconfiguring bus transportation schedules for all students. It can foul up after school extracurricular schedules as well.
And parents don't like the thought of elementary students standing at the bus stop on cold, dark Minnesota mornings, so high schoolers can start their day later.
That's why the St. Paul School District is carefully studying such a change and developing several scenarios to consider, said Jackie Turner, the chief engagement officer for the district.
"We're going to be thoughtful in our decision, we're going to engage parents and the community, we're not going to make a hasty decision," she said.
Turner said district officials are well aware of the benefits a later start time would have for high school students, but such a change, even if approved, would be years away.