TWO YEARS AFTER the defeat of a hotly debated proposal to push back start times for high school students, Fairfax County school officials want to revisit the issue. The reason the idea won’t go away is that it makes too much sense. Every bit of scientific research and experience shows that teenagers have different sleep patterns and that later start times are beneficial to students, schools and the community.

The Fairfax County School Board directed Superintendent Jack D. Dale last week to report on how other school systems, including Arlington’s and Loudoun’s, have managed to have high schools start later than those in Fairfax. Most high schools in the county, as The Post’s Donna St. George reported, start at 7:20 a.m., which translates into students having to be up and ready for school buses as early as 5:45 a.m. By contrast, Arlington starts high schools nearly an hour later, and most high schools in Loudoun begin at 9 a.m.

Fairfax is far larger — it has more students than any other district in Virginia — so clearly the logistics are more difficult. Indeed, as Board Chairwoman Jane K. Strauss (Dranesville) noted, “If it was easy, we would have done it 20 years ago.” No doubt Ms. Strauss was thinking of the untold hours that went into the study and debate of a proposal in 2009 to push back the bell schedule by an hour. It was ultimately rejected as too disruptive to the other grades and to extracurricular activities.

The board, though, is right to persist in trying to bring about sensible reform as to when high school students begin classes. Students who are sleep-deprived achieve less and are more likely to suffer from depression or obesity or to have issues with drugs and alcohol. Because adolescents have biorhythms set on a cycle different than those of adults or younger children, the problem is not so easily solved as by telling teenagers to go to bed earlier. Figuring out a way for older students to be in class when they are most alert is to everyone's benefit. Mr. Dale is to report back to the board in June.