FIGURE 3.

Age, period, and cohort effects on the probability that US adolescents regularly report adequate sleep per night from 1991 to 2012 in nationally representative samples (N = 270 719). The cohort and period time–scale contains risk ratio estimates for the effect of cohort (far left line) and period (far right line). Thin lines indicate 95% confidence intervals. The cohort estimates were compared with a referent cohort of 1980; thus, the lines can be interpreted as the average proportion of adolescents obtaining adequate sleep regularly, regardless of time period, compared with the average proportion in 1980. The period estimates were compared with a referent period of 1995; thus, the lines can be interpreted as the average proportion of adolescents obtaining adequate sleep regularly in that year, regardless of cohort, compared with the average proportion in 1995.