And research consistently shows that teenagers perform better if you start school later in the day than 7am. E.g., http://journals.sagepub.com/doi/abs/10.1177/0192636502086633... "shifted the school start timefrom 7:15 a. m. to 8:40 a. m. This article examines that change, finding significant benefits such as improved attendance and enrollment rates, less sleeping in class, and less student-reported depression."

https://www.tandfonline.com/doi/abs/10.1080/1540200070126380... "Students at the late-starting school reported waking up over 1 hr later on school mornings and obtaining 50 min more sleep each night, less sleepiness, and fewer tardies than students at the early school."

https://www.aeaweb.org/articles?id=10.1257/pol.3.3.62 "Results show that starting the school day 50 minutes later has a significant positive effect on student achievement, which is roughly equivalent to raising teacher quality by one standard deviation."