A New Jersey high school decision to start classes 40 minutes later in September is refocusing attention on longtime concerns over whether teenagers are getting enough sleep. Chatham High School is moving the start of its school day from 7:40 a.m. to 8:20 a.m., for the 2022-2023 school year, amid a pending discussion in the New Jersey Legislature on a bill that would establish 8:30 a.m. as the earliest possible high school starting time. Only one other state has an average start time later than 8:30, statistics show. This is not a new discussion, in New Jersey and elsewhere, and the stresses o…