High school is a time where many students develop time management skills and find independence in falling into their own personal daily routines. In contrast, school start times are set in stone, can change from year to year, and are what dictate students’ schedules. This research study will explore what makes an adolescent an “early bird” or a “night owl,” and use attendance data to determine how these individual student sleep preferences affect students’ morning attendance across different school years with varying start times.