TWO MORE area school districts have decided to study later start times for their high school students. That’s evidence of the growing demand that school schedules be shaped not by mindless adherence to tradition but by what is best for student learning. Let’s hope that school officials who have undertaken examinations of this issue are not just going through the motions.

Anne Arundel and Howard are the latest districts to undertake studies of later bell times for older students. This comes in response to complaints from parents, who point to evidence showing the benefits of start times that are more in sync with teenagers’ natural sleep patterns. The decision, as The Post’s Donna St. George reported, comes after officials in Montgomery and Fairfax decided to pursue the issue. Fairfax seems especially serious, establishing a goal of start times after 8 a.m. and enlisting a consultant to help implement a plan. Montgomery has formed a work group, which has met several times and is expected to make recommendations by June.

The four school systems start high school classes between 7:17 a.m. and 7:25 a.m., which requires many students to be up and headed to school by 6 a.m. or soon after. In pushing for start times after 8 a.m., parents point to the persuasive body of research establishing that adolescent sleep patterns make it hard for them to go to sleep or wake up early. Biology — not a parent’s nagging or a teen’s self-discipline — is the determining factor. Schools with later start times have demonstrated the benefits to students, schools and communities in the way of better academic performance, less tardiness and absenteeism and lowered risks for depression and car crashes.

Both Montgomery and Fairfax have studied later start times in the past, but the efforts were scuttled by opposition and the complexity of rearranging bus schedules and after-school activities. Fundamental change to community routines isn’t easy. But other districts around the country — including Loudoun and Arlington counties — have shown that later start times are beneficial and feasible.