MINNEAPOLIS — A new study found that when high schools switch to a later start time, there is an improvement in student grades, attendance and overall student health.

The three-year study by the University of Minnesota examined data from more than 9,000 students at eight high schools in Minnesota, Colorado and Wyoming.

It found that later start times boosted attendance, standardized test scores and academic performance in math, English, science and social studies. Students with the later starts also consumed less caffeine.

The study, released Wednesday, also found that after Jackson Hole High School in Wyoming switched to a later start, it saw a 70 percent drop in the number of car crashes involving teen drivers. Jackson Hole shifted to an 8:55 a.m. start time, the latest start of all schools studied. The study, funded by the Centers for Disease Control and Prevention, found that 66 percent of students at high schools with an 8:55 a.m. start get the recommended eight or more hours of sleep. When schools start at 7:30 a.m., an average of 34 percent of students get the recommended amount of sleep.

“Even a start time of 8:35 a.m. allows 57 to 60 percent of students to get eight or more hours of sleep, which is an important health benefit for a majority of students,” Kyla Wahlstrom, director of the university’s Center for Applied Research and Educational Improvement, said in a statement. “Local school districts, school personnel, parents and students need to understand the importance of sleep and to make choices using the knowledge from this and other studies.”