THE SIGNATURES on a petition calling for a later start time for Montgomery County high school students have yet to be delivered to school officials, but already the groaning has started, about the difficulty of working out the logistics and changing people’s habits. Given past failures to bring about change, why should any time or energy be expended on this?

Here’s one reason: There is incontrovertible evidence of the benefits to students, schools and communities of start times that are more in sync with adolescent sleep patterns. Montgomery school officials should, at the very least, undertake a study of this important issue.

More than 9,700 signatures have been collected on an online petition, to be presented Tuesday to the Board of Education, that urges a change in the current 7:25 a.m. start time to 8:15 a.m. or later. The campaign, launched in October, has tapped a groundswell of support from parents who, like petition organizer Mandi Mader, are sick and tired of seeing their children sick and tired. Ms. Mader, a psychotherapist who found sleep deprivation exacerbating the problems of her teenage patients, told The Post’s Donna St. George that Montgomery schools, which do so much right, are “behind the curve and not up to best practices on this.”

Clearly, it wouldn’t be easy to reconfigure Montgomery’s massive transportation system or to change long-held routines or to please everyone — factors that doomed Montgomery’s previous efforts for later high school bell times in the late 1990s. Those difficulties, though, cannot justify ignoring or tolerating the harm to teenagers caused by unhealthy start times. Those who would argue that parents simply need to do a better job of policing when their kids go to bed ignore the convincing body of research that shows adolescents have different biological sleep patterns that make it hard for them to go to sleep or wake up early. The sleep deprivation that results from having to get up before the crack of dawn plays out in lower academic performance; tardiness and absenteeism; and increased risks for depression or car crashes.

Such evidence has caused school systems around the country to find creative — and often low- or no-cost ways — of holding classes at later, healthier hours suited to adolescents. Indeed, one need look no further than Loudoun or Arlington counties. Fairfax County, similar in many respects to Montgomery, has set later start times as a goal and is enlisting a consultant to help devise a plan. Montgomery school officials should take seriously the concerns being raised and look for ways to address them.