Parents in Montgomery County made impassioned pleas Thursday for later high school starting times, sharing personal stories of teenagers who barely function in the pre-dawn darkness, fall asleep during early classes and fight chronic exhaustion.

At two public hearings, an overwhelming majority supported shifting the hours of the school day, some bringing handmade placards and others attending with pajama-clad children. Many cited research findings. Some called for political courage.

Dozens of people testified, including students, educators and sleep experts.

“This change would benefit every high-schooler in the county,” said Shannon Lindstrom, a mother of four who pointed to a district survey that found 78 percent of parents favored a proposal — no longer on the table — to shift bell times from 7:25 a.m. to 8:15 a.m. “That’s a mandate to act.”

The hearings came 2 1/2 weeks before Montgomery’s school board is expected to vote on the issue.

The district has offered five main options for changing school hours, each said to cost less than $10 million a year. Superintendent Joshua P. Starr recommended that the board consider only no-cost proposals, and his choice was one that would delay the start of all school days by 20 minutes.

“Twenty minutes is really not enough,” said parent Francesca Goodall, whose family made a fluorescent sign drawing attention to how much the district recently spent to buy Chromebooks — part of a technology initiative estimated to cost $15 million for the first year — in arguing that the school system should invest in later start times.

Many who testified said school leaders need to do more than the 20-minute push-back that Starr proposed, but not everyone was specific about which option they prefer.

Stephanie Weishaar, a mother of two, recounted her daughter’s 5:30 a.m. wake-ups and the big difference after she graduated from Richard Montgomery High School last year and went to college. Dark circles under her eyes are gone. The teen is healthier, she said.

Weishaar said her daughter’s explanation was that she gets “so much” more sleep at MIT. “Please take a moment to let that sink in,” Weishaar said. “A freshman at MIT is better-rested than in her days at MCPS.”

Students who attended the hearings also described early-morning difficulties. Fourteen-year-old Bryce Hauver-Reeves said in an interview that with a semester of ninth grade behind him, first-period classes remain brutal.

“Kids will just be staring at the teacher,” he said. “They’re not asleep, but they’re completely zoned out and not paying attention.”

Daniel Lewin, associate director of sleep medicine at Children’s National Medical Center, said chronic sleep loss in teens is at an all-time high, with 60 percent of ninth-graders and 77 percent of 12th-graders getting insufficient sleep.

Although objections to later bell times were few at the hearing, some parents asked that elementary school students not be scheduled too late in the mornings or the afternoons. Michelle Edwards, a Rockville mother of a second-grader, urged school leaders to keep in mind the cost of day care and the struggles of working parents.

Allison Erdman, a Montgomery high school teacher, said some of the proposed changes could take a toll on educators, a number of whom don’t live in high-cost Montgomery and would not be able to accommodate schedule shifts at odds with long commutes and children’s schooling in other areas.

“Some highly qualified teachers, myself included, would be forced to look for a job in another county,” she said.

Pressing for later starts at high schools, Larry Ottinger, a father of two from Chevy Chase, told the board that the research is clear and asked the members to respond to the science and the outpouring of parent concerns.

“This is real,” he said. “This is serious. This is a top priority.”

The American Academy of Pediatrics recommends start times of 8:30 a.m. or later for middle and high schools. Experts say that adolescents are biologically wired for later bedtimes and wake-ups and that a lack of sleep is linked to increased risks of mental health issues, poor school performance and car crashes. Teenagers need between 8 1/2 and 9 1/2 hours of sleep a night, according to experts.

During the second of two hearings Thursday, parent Barbara Lovitts stood in the back of the room with a poster reading: “The solution is simple: Get a new superintendent.”

“It’s all about political will,” she said. “Starr doesn’t have the interest or the will.”

Schools spokesman Dana Tofig declined to comment on the sign but said there are many complex issues related to running a school system and difficult decisions that need to be made.

“While not everyone will agree on every decision or recommendation, it is important that we model civility and respect for our students,” Tofig said.

Myron Marlin, a Bethesda father of two, wrote his support for later high school hours into a 16-stanza poem he composed with the help of his wife. As he read stanza after stanza, others at the hearing joined in for his refrain:

“Please let our kids get more sleep.”