Beginning on Tuesday, the bell will ring on many Santa Rosa campuses, marking a new school year. Summer will end, and students who don’t want a tardy slip — or whatever passes for one these days — will have to be in their seats by 8 a.m. Yet their bleary eyes will belie an important truth: Teens need more sleep.

The state Legislature has been kicking around a bill to require that middle and high schools start classes no earlier than 8:30 a.m. Under the bill, students, starting in 2020, would get a few crucial extra minutes of sleep that their developing brains and bodies need. The change would not apply to the “zero period” available in Santa Rosa and other schools, but those starting times would likely move back from 7 a.m. as well.

The bill, SB 328, passed the state Senate with support from Sens. Bill Dodd, D-Napa, and Mike McGuire, D-Healdsburg. It now awaits action in the Assembly.

The idea has critics, especially among parents. Families have morning routines that they’ve perfected over years. Pushing back the start time would disrupt those routines and could affect adult work schedules.

The more cantankerous adults fall back on their own experience. Waking up early was good enough for them, they say. Back in their day, they claim they were out of bed before the sun rose, ready to walk miles uphill through rain and even snow — well, maybe not in Sonoma County. But the point is many believe pushing back the start time would be coddling teens.

Science, however, says that’s exactly what we should be doing.

Over the past few decades, medical research has established that teenagers need more sleep than adults. The UCLA Sleep Disorders Center reports that the average teen needs about nine hours of sleep per night to remain healthy. Short of that, physical weariness, depression and other emotional and cognitive disorders can occur. Researchers at the University of Minnesota found that when schools start later, students perform better in class and in life.

An 8:30 a.m. start time would be only an opportunity. Parents and students would have to take advantage of it, starting by getting to bed on time. If teens stay up later because they can sleep in longer, then the 8:30 a.m. launch would be for naught. Parents and students would still need to make sure that the Xbox, computer and cell phone are off and that homework is finshed early enough to ensure a good night’s sleep.

Many families also would need to develop new routines, and employers should accommodate parents in the morning.

Santa Rosa City Schools officials note that changing the start time would affect the afternoon schedule as well. A later end time would have impacts on after-school activities such as sports and clubs. Students who work part-time jobs might also face new challenges.

None of these is an insurmountable problem, however. Routines can change. Schools can adapt. Teen only get one shot at growing up healthy. The state Legislature can help improve their chances of success in health and in class by approving SB 328.