High school attendance went up and some academic performance improved after District 833 switched to later morning start times.

Those were key conclusions in a study by the University of Minnesota’s Center for Applied Research and Educational Improvement. The multi-year research analyzed the effect a later start time had on student health and school work.

Dr. Kyla Wahlstrom, who led the study, said sleep is a “biological imperative” and an inadequate amount of sleep can affect emotion, health and academic performance. That applies to teenagers, who due to biological changes need more sleep at a later time, research has shown. The study noted that adolescents need 9.25 hours of sleep but on average they get about 8.3 hours at age 11 and less as they get older, to under 7 hours by age 17.

“They’re just not developmentally ready to be awake at 6 in the morning,” Wahlstrom told the District 833 School Board when she presented the study findings earlier this month. “That is a fact.”

The university center in recent years studied the effect of later start times at five districts: East Ridge, Park and Woodbury high schools; St. Louis Park High School; Mahtomedi High School; and two schools in Boulder, Colo. Researchers also surveyed students about their sleep habits.

Among most participating schools, District 833’s three buildings had the latest start time. District 833 made its switch to an 8:35 a.m. start in the fall of 2009. Park and Woodbury had started at 7:35 a.m. the previous year. East Ridge was new in the fall of 2009.

“Every change has an incremental benefit,” Wahlstrom said. “The larger the change, the larger the benefit.”

Among the study’s findings:

- Average attendance in the three District 833 schools increased after the late start change.

- There was a significant decrease in tardies, though the study could not conclude if that was a reduction in first-period tardies that could be attributed to the later start time.

- There were positive gains in student GPA, but there was no consistent pattern, so it was unclear what factors contributed to the improvement.

- More students scored “proficient” on a standardized math score after the start time change.

- District 833 students get about 7.9 hours of sleep on school nights and 9.3 hours on weekend nights.

- Sixty percent of Park students students sleep at least 8 hours a week. It’s 58.9 percent at East Ridge and 57 percent at Woodbury.

- Half of local students have a TV in their bedroom and 89 percent of them have a telephone or cellphone in their bedroom. Wahlstrom said having electronics in the bedroom is “problematic” for good sleeping habits.

Responding to an argument against a later start time, Wahlstrom said starting an hour later does not mean kids will just stay up later. Research has shown they don’t go to bed later but they do wake up later, resulting in more sleep overall.

“They don’t stay up an extra hour because they’re tired; they fall asleep,” she said.

School Board Chairman Ron Kath said that when the board approved the start time change he saw the switch as a “leap of faith” that it would benefit students. The research has supported the change, he said, and it could help inform school officials on future decisions.

“If we get into a situation where we do have budget constraints, now we have some data to lean on,” Kath said. “It’s our data.”

Superintendent Keith Jacobus, who started with the district after the start time had been changed, said he is proud of the school system for making the change and for doing “everything we can” to help secondary school students be prepared when they get to class.