This research examines the influence that early start times have on student achievement among students at the USAFA. Researchers found that having a first period class (between 7 am and 7:50 am) has a significantly negative effect on student achievement. The negative impact diminishes as start times are delayed but is still present. Students that have a first-period class not only performed poorly in the first class of the day but continued to have poor performance throughout subsequent courses of the day, particularly when compared to students that did not have a first-period class.
Source: American Economic Journal http://faculty.econ.ucdavis.edu/faculty/scarrell/sleep.pdf
Carrell, S., Maghakian, T., & West, J. (2011). A's from Zzzz's?: The causal effect of school start time on the academic achievement of adolescents. American Economic Journal. Economic Policy, 3(3), 62-81. doi: 10.1257/pol.3.3.62