This research indicates that implementing later school start times is associated with improved sleep, grades, and attendance among high school students. Later start times allow students to have a better chance at achieving the recommended amount of sleep for adolescents and, in turn, results in well-rested, alert, and punctual students.
Source: Science Advances: https://advances.sciencemag.org/content/4/12/eaau6200
Dunster, G.P., De La Iglesia, L., Ben-Hamo, M., Nave, C., Fleischer, J.G., Panda, S., & De La Iglesia, H.O. (2018). Sleepmore in Seattle: Later school start times are associated with more sleep and better performance in high school students. Science Advances,4(12), 1-7. doi: 10.1126/sciadv.aau6200