This research observes a school that is one of the first to implement start times as late as 10 am. Over a four year span, students were assessed during school years that started at 8:50 am, 10 am for two years, and back to 8:50 am. The later start time was associated with students making good academic progress, which was equivalent to a significant 20% increase in the national benchmark, as well as a significant decrease in absences due to illness. When start times reverted to 8:50 am, a decrease in student success, and an increase in absences occurred.
Source: Frontiers in Human Neuroscience https://www.frontiersin.org/articles/10.3389/fnhum.2017.00588/full
Kelley, P., Lockley, S.W., Kelley, J., & Evans, M.D R. (2017). Is 8:30 am still too early to start school? A 10:00 am school start time improves health and performance of students aged 13-16. Frontiers in Human Neuroscience,11, 588. doi: 10.3389/fnhum.2017.00588