Figure 3.

Sleep schedule and duration on school nights and non-school nights by age 17 school-schedule type. (A, B) On school nights, both traditional (blue) and college-style (red) students went to bed later at 17 (filled) versus 15 (unfilled), but college-style student rose later at age 17 (A). Thus, only traditional-school students reduced sleep duration at 17 (B). (C, D) On non-school-nights, both traditional and college-style students went to bed later and rose at the same time at age 17 versus 15 (C), but only college-style students reduced sleep duration (D). Box (median with first and third quartile) and whiskers (95% confidence interval) are used for bed- and rise-times; mean (boxes) with standard deviation (error bars) is used for sleep duration. P-values with black bars indicate paired, within school-type comparisons between ages 15 and 17. # (p<0.05) and ## (p<0.01) indicate significant differences between traditional and college-style students at age 15 or 17. All comparisons adjusted for sex, parental education, and multiple comparisons.