AMHERST – Middle and high school students here will have a chance to get a little more sleep in the morning, beginning September of 2020.

At its January meeting, the board for SAU 39 agreed to make the start times a half hour later. The decision was based on research showing later school start times can improve teenagers’ physical and emotional health, academic performance and safety on the roads.

The change will also affect the elementary schools, Clark-Wilkins and Mont Vernon Village School. Both will start around a half hour earlier.

A district start-time committee had originally recommended that all the elementary schools’ start times be 30 minutes later, but parents and teachers of the younger children had objected, saying there are problems with having them in school later in the afternoon when their energy wanes.

Under district guideline discussed at the board’s December meeting, the elementary schools would start no earlier than 8 a.m. and at the middle and high school the day would end as close to 3:30 p.m. as possible.

Current start times are 8:25 for Clark-Wilkins, and 7:25 for the middle and high school.

The guidelines also say the impact to student athletes and other activities be limited as much as possible and before and after care options for parents be expanded.

The SAU board is expected to develop an implementation plan by November 2019.

At a community forum in December, retired middle school principal Porter Dodge said school officials started talking about changing start times at least 30 years ago, when teachers noticed students were tired.

With the early starts, “we’re not doing them good service,” he said.

Amherst is one of the few districts in New Hampshire that have made the change, joining the Portsmouth, Keene and the Oyster River districts.

The Milford School Board also has a start-time committee working on a possible change. The high school and middle school now start at 7:40 and 7:35 a.m. respectively.

The Conval school district will have an article on the district warrant in March, for $808,000 to pay for more buses to make the middle and high schools’ start time one hour later. They now start at 7:35 and 7:25.

The American Academy of Pediatrics recommends that middle and high school students start school after 8:30 a.m. to better align with their bodies’ sleep rhythms. Adolescents who don’t get enough sleep often suffer physical and mental health problems, it says, show a decline in academic performance and have an increased risk of obesity and automobile accidents.

Teenagers are said to need nine to 10 hours of sleep each night, but only 31 percent get enough, according to the Centers for Disease Control and Prevention.