BIDDEFORD — Citing a desire to give students a better chance to learn, the school boards of Biddeford, Saco and Dayton agreed Wednesday to push back start times for middle and high school students to 8:30 a.m. or later.

Middle and high school students in those towns now start school between 7:30 a.m. and 7:45 a.m. The change will begin with the fall semester.

The changes are part of a national trend, and are recommended by a variety of medical agencies.

The joint meeting at Pepperell Mill drew dozens of parents and medical professionals, who presented data that suggests teenagers who begin their school day at 8:30 a.m. or later learn better, live healthier lifestyles, are less prone to athletic injuries and less likely to engage in risky behaviors. No one from the public spoke against the proposal.

Students in lower grades will begin earlier than they do now, from 7:45 a.m. in Dayton to 8:10 for some schools in Saco. They now start school between 8:10 and 8:30 a.m. Research suggests teenagers function better later in the morning than younger students.

The joint meeting of the school committees also involved administrators from Thornton Academy in Saco, where students from Saco attend high school. Students from Dayton attend middle and high school at Thornton. Thornton Headmaster Rene Menard endorsed the changes.

The Dayton and Saco boards passed the proposal unanimously. Biddeford passed the measure 7-2, with committee members Lisa Vadnais and Crystal Blais voting against it.

Old Orchard Beach had already shifted its start times for the middle and high schools from 7:30 to 8 a.m. for the current school year. Scarborough, South Portland, Yarmouth and SAD 51 (Greely High School) also are considering later start times. School departments in Westbrook and Cape Elizabeth have pushed back start times.

U.S. Centers for Disease Control and Prevention recommends middle and high schools start no earlier than 8:30 a.m. According to the latest-available CDC report on the topic, Maine’s average high school start time is 7:53 a.m., 10 minutes earlier than the national average.