The opening school bell could ring later in the morning at several southern Maine high schools and middle schools this fall based on U.S. Centers for Disease Control and Prevention recommendations that warn early start times are detrimental to student health.

Grass-roots organizers promoting later start times mustered support for the idea this past fall, and the movement has gained steam. Now some local school boards will be voting on specific proposals this winter and spring for changes in the 2016-17 school year.

Tracey Collins, a parent of a Saco Middle School student and grass-roots organizer, said the effort is paying off, as now there seems to be wide support for the idea.

“I’m really optimistic that we’re going to do the right thing for the kids,” said Collins, who heads up the Saco chapter of Start School Later, a national advocacy group. “The science is so overwhelming, and it’s really becoming negligent for schools to ignore the data.”

So far, school boards in Saco, Biddeford, Old Orchard Beach, at Thornton Academy in Saco, Scarborough, South Portland, Yarmouth and SAD 51 (Greely High School) are mulling later start times for 2016-17 or in future years.

The CDC 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 of 8:03 a.m. Many Maine high schools start at 7:30 a.m. or earlier. Nationally, at least 200 schools instituted later starting times over the past few years.

Numerous research studies have proven that early starting times for teenagers are harmful to their health, because the developing brain is wired differently than an adult’s. For a teenager’s brain, 7 a.m. is equivalent to 4 a.m. for an adult, according to the CDC. Also, teens need more sleep than adults, at least 8½ hours compared to seven hours for an adult. In addition, teens’ biological clock means they feel sleepy later in the evening than elementary school students, which is why teens have a difficult time falling asleep before 11 p.m.

That means teenagers, unlike adults, cannot simply go to bed earlier and still be alert at the beginning of the school day, according to the CDC.

Starting school too early has led to higher rates of adverse health problems, including obesity and depression, and has also been shown to lead to more frequent car accidents when drowsy teens drive to school, according to the CDC. In addition, sports performances are compromised when students get too little sleep, as reaction times decline and the body does not heal as well from sports injuries.

Studies correlate improved student performance to well-rested teens, especially during morning classes, and reduced use of drugs and alcohol, according to scientific research.

The message is hitting home, Collins said, once parents and school officials see the science.

Collins and others have organized several presentations to school boards, hosted community forums and organized a regional meeting in October that attracted representatives from 14 school districts. Local doctors, school nurses and sports physicians have also joined in the effort.

The York County schools worked together to organize a coordinated proposal for 8:30 a.m. start times. Jeremy Ray, Biddeford’s superintendent, said school boards are on track to vote for the later start times in March in Saco, Biddeford, Old Orchard Beach and at Thornton Academy. 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

“Certainly this is a big change for everyone,” Ray said. “The regional approach has been huge. It would be very difficult for us to have done this on our own.”

Ray said while some parents were concerned about sports schedules, they ran a spreadsheet of all the games in the school year to see how many games would be affected by school releasing students later. Ray said the impact was “minimal,” and practice time was unaffected.

In South Portland, the high school has one of the earliest start times in the region at 7:25 a.m.

South Portland Superintendent Ken Kunin said a committee has been working on the issue for a few months, and a survey was taken of middle and high school students.

The results show 49 percent of high school students who took the survey were getting seven hours of sleep or less per night, a full 90 minutes less than CDC recommendations.

“Large numbers of our students are sleep-challenged, which (is) highly correlated with problems with depression, anxiety, obesity and could impact academic performance,” Kunin said.

Kunin said while there’s no official proposal yet, if a change can be made that’s budget-neutral and doesn’t greatly affect elementary school starting times, it could be implemented for 2016-17. Kunin said it’s possible that an 8 a.m. starting time for high school could be done by altering some bus runs, and a proposal could go before the school board this spring that would alter the start times for next year.

Meanwhile, the SAD 51 school board is slated to vote at its Feb. 22 meeting to have Greely middle and high schools start at 8 a.m. instead of 7:30.

Yarmouth also formed a committee to study the idea, according to news reports, and Scarborough schools have held public forums on the topic.

School departments in Westbrook and Cape Elizabeth have pushed back start times in recent years, also because of the studies that show early start times are detrimental.