In the Garrett Park Estates section of Kensington, Walter Johnson High School students board an early morning school bus. Montgomery County is considering starting the high school day later. (Photo by Susan Biddle) (Susan Biddle/FOR THE WASHINGTON POST)

Montgomery County’s schools chief recommended Tuesday that the school board consider only no-cost approaches for moving high school bell times later in the morning, backing a proposal that would give teenagers 20 more minutes of sleep every morning.

Superintendent Joshua P. Starr said the most reasonable option would push back school openings by 20 minutes for students in all grades, which would mean the district’s 25 high schools would start classes at 7:45 a.m. instead of at 7:25 a.m.

“It gets us part of the way there,” Starr said. “It’s a partial measure, but it does do something to address the issue.”

A 20-minute change was among five options detailed in a report the school system released Tuesday, all of them said to cost less than $10 million a year in keeping with the school board’s request in June. School leaders are now seeking public comment.

The new proposals mark the latest phase of an effort dating to 2012, when Montgomery parents launched an online petition calling for later start times, saying more sleep would benefit teens’ health and well-being.

Supporters of later start times at high schools point to a growing body of research that shows teens are biologically wired for later bedtimes and later wake-ups. Experts say that lack of enough sleep is linked to lower academic performance, absenteeism, and an increased risk of depression and car crashes. Teenagers need between 8  1 /2 and 9  1 /2 hours of sleep a night.

Mandi Mader, a Garrett Park parent who launched the petition, called Starr’s embrace of a 20-minute change “totally inadequate.” Mader said her group would continue its effort. “At least one more hour is needed for better mental and physical health and safety,” she said. “The discussion needs to continue, and there needs to be a sense of urgency about it.”

School officials say transportation is a major factor in the cost of the proposals. The district’s staggered school start times allow buses to transport one wave of students and then another. Buses used to transport high school students, for example, are then used again for middle schoolers and later for those in elementary school.

The suggested approaches come at a time of economic uncertainty, as state and county officials have projected significant revenue shortfalls. Starr said that although he wishes the district had funds to do more, “I don’t have that luxury, and most people, I think, understand that.”

Board of Education President Patricia O’Neill said she had not yet made a decision on the issue but that economic strains could be limiting. “To me, I would’ve liked to have come up with something that gave a bit more relief,” she said, noting that a modest adjustment is a step in the right direction. “It’s like resetting the snooze button on your alarm clock.”

The proposal Starr supports includes an alternative scenario that would shift schedules at all schools by 35 minutes and have a minimal fiscal impact.

In fall 2013, Starr proposed shifting the opening bell at county high schools to 8:15 a.m., part of a plan that also extended the length of the elementary school day. After public input and more study, he withdrew his support, saying in June that the plan’s cost — more than $20 million — was too high and that community feedback was mixed.

Montgomery’s school board asked Starr to come back with lower-cost options.

The ideas that emerged Tuesday included a proposal to send the youngest students to school first every morning, with elementary schools starting before middle and high schools. That proposal comes with four possible models, costing from $2.6 million a year to $5.2 million a year, with elementary start times as early as 7:35 a.m. or 7:45 a.m.

A third option would rework Starr’s original recommendation, which proposed having middle school students arrive at schools first. It would cost between $5.2 million and $5.85 million.

A fourth option would split the high school day so that some students start at 7:25 a.m. and others at 9:05 a.m. The cost of the high school split was unspecified, and transportation would not be provided to students opting to start later.

A final proposal would leave school hours unchanged but examine the possibility of offering other steps that might help students get more sleep, including having abbreviated schedules and taking online courses.

The proposals released Tuesday are scheduled to be detailed next Tuesday at a school board meeting, with public hearings set for Jan. 22. A board vote is expected next month.