Abstract
This cross-sectional study utilized responses from 46,537 students enrolled in grades 9 through 12 in 166 high schools across the state of Colorado via the 2019 Healthy Kids Colorado Survey to: (1) quantify the association between high school start times and student sleep duration and (2) investigate the associations between school start times and student mental health. Descriptive and bivariate analyses were used to investigate associations between school start times and self-reported demographic, sleep, and mental health factors. Survey-weighted multivariate regression modeling was used to investigate associations between school start times, sleep duration, and mental health. Schools with late start times (≥8:30 a.m.) saw 32.2% (95% Confidence Interval: 29.5-35.0) of students sleeping 8 h or more relative to 23.2% (22.0-24.4) in schools with very early start times (<8:00 a.m.). For every 15 min later school start time, students' sleep duration was 4.6 (3.4-5.9) min longer. Students attending schools with very early start times had 1.10 (0.95-1.27) times the odds of attempting suicide compared to those attending schools with later start times, while students at schools with early starts (8:00-8:29 a.m.) were associated with 1.11 (0.98-1.27) times the odds. Schools with later school start times had a statistically significantly higher proportion of students sleeping 8+ hours. Schools with start times before 8:30 a.m. had 10-11% higher odds of students attempting suicide compared to schools with late start times, though these differences were not statistically significant. Student mental health should continue to be investigated when assessing the potential impacts of delayed school start times.