Impact of School Start Time Delays and Learning Modality on Sleep Timing and Duration During COVID-19.

Objectives: To assess the impact of a school start time (SST) delay on adolescent sleep health during the COVID-19 pandemic, and whether there were differences by learning modality.

Methods: Data were collected from a longitudinal study evaluating sleep, education, and health among high school students in Georgia in 2020. Paired t-tests and multivariable linear regression analyses were conducted to examine changes in sleep duration and timing among 9^th grade students (n = 134) and their association with the learning modality (remote vs. in-person learner).

Results: Students' school day wake times were 1.5 hours later, school night sleep duration was 1.2 hours longer, and social jetlag was 0.9 hours shorter after the school start time delay (all P < .05). The learning modality was a significant predictor of changes in sleep timing but was not associated with changes in sleep duration.

Conclusions: Delayed school start time was associated with positive changes in adolescent sleep health during the COVID-19 pandemic. Sleep timing was affected by the learning modality, however in-person and virtual students had similar gains in sleep duration. Learning modality may be more beneficial for adolescents with early school start times to promote healthier sleep habits.