Fig. 5: Students with morning classes on more days of the week had a lower grade point average.
From: Early morning university classes are associated with impaired sleep and academic performance
a, The distributions of grades are shown for courses with class sessions that took place exclusively in the morning (starting before 12:00), exclusively in the afternoon (starting at 12:00 or later) or in both the morning and afternoon. The number of morning-only (AM), afternoon-only (PM) and morning/afternoon (MIX) course grades is indicated on the plot. b, Box plots show the distribution of grade point average by the number of days per week that students had morning classes. Boxes show the median and interquartile range. Whiskers show the 10th and 90th percentiles. Sample sizes are displayed at the top of each bar. Effect sizes (Cohen’s d) with 95% CIs and the bootstrap sampling distributions are plotted for days with morning classes (1 to 5 days) versus having no morning classes. Data were compiled from 33,818 unique students over six semesters.
