The research is clear: Teenagers are not early morning people. For more than two decades, studies have conclusively shown that adolescents are more alert and ready to learn during mid- to late-morning and afternoon hours.

With that in mind, the St. Paul school board recently made its strongest move yet toward later school start times for the district’s older students. In a 4-3 vote this week, the board directed its administration to develop a plan for start time changes in 2018-19 that are in the “health and academic best interests” of students.

It’s high time. As many other districts have learned, letting older students sleep in a little longer better aligns learning with teenage body rhythms — a change that leads to improved academic performance.

Though it’s in the best interest of teens, the schedule adjustment is not a simple policy change in St. Paul. Modifying the district’s three morning bus runs to pick up younger students earlier and older kids later will cost an additional estimated $2 million to $4 million — funds that could be hard to find in a budget that could face a $24 million shortfall next year. Allowing all students to begin classes at 8:15 a.m. or later would cost twice as much in busing costs, officials say — even if the district uses more Metro Transit buses to transport students.

In addition to budget issues, bus companies that contract to provide service for the schools say they have a hard time finding enough part-time drivers to fill current positions. Employing 50 or more new employees to add more runs would be even harder.

And even though elementary children’s body clocks are better set for the earlier times, many parents of younger kids object to having their little ones waiting for buses before 7 a.m. For these reasons and others, St. Paul school officials have discussed later start times off and on for years, but have failed to make it happen.

That should change. Yes, there are difficult trade-offs, and school officials will likely consider phasing in changes to give families time to adjust. But removing obstacles to student achievement should be the focus.

Other Minnesota school districts faced with similar complexities found ways to work through the challenges — even if it meant that some families were initially unhappy with start-time changes. Edina and Minneapolis moved their start times nearly 20 years ago, and since then districts including South Washington County, St. Louis Park and Wayzata have followed suit.

Should St. Paul make the smart adjustment, it will join the majority of other districts that already have later start times. According to data collected by the Minnesota Sleep Society, only 37 state districts have start times before 8 a.m.; that affects about 82,000, or 34 percent, of all Minnesota 9th-12th graders.

The St. Paul board has positioned the district to take an important step for high school students. Now officials must finally turn the talk into policy.