WASHINGTON (AP) — A later start to the school day could help teenagers get the most from their classroom time and local districts should consider delaying the first bell, Education Secretary Arne Duncan said Wednesday.

School districts would still be free to set their own start times, Duncan insisted in a broadcast interview, but he pointed to research that backs up his comments that rested students are ready students. Duncan said he would not be telling local school leaders when their first bells should ring and said it was up to local leaders to make the decisions on their own.