Abstract
The amount of time available in a day is fixed, and consequently, sleep is often sacrificed for waking activities. For college students, daily activities, comprised of scheduled classes, work, study, social, and other extracurricular events, are major contributors to insufficient and poor-quality sleep. We investigated the impact of daily schedules on sleep-wake timing in 223 undergraduate students (age: 18-27 years, 37% females) from a United States university, who were monitored for ~30 days. Sleep-wake timing and daily recorded activities (attendance at academic, studying, exercise-based, and/or extracurricular activities) were captured by a twice-daily internet-based diary. Wrist-worn actigraphy was conducted to confirm sleep-wake timing. Linear mixed models were used to quantify associations between daily schedule and sleep-wake timing at between-person and within-person levels. Later scheduled start time predicted later sleep onset (between and within: p < .001), longer sleep duration on the previous night (within: p < .001), and later wake time (between and within: p < .001). Later schedule end time predicted later sleep onset (within: p < .001) and shorter sleep duration that night (within: p < .001). For every 1 hour that activities extended beyond 10 pm, sleep onset was delayed by 15 minutes at the within-person level and 40 minutes at the between-person level, and sleep duration was shortened by 6 and 23 minutes, respectively. Increased daily documented total activity time predicted earlier wake (between and within: p < .001), later sleep onset that night (within: p < .05), and shorter sleep duration (within: p < .001). These results indicate that daily schedules are an important factor in sleep timing and duration in college students. Clinical Trial: Multi-scale Modeling of Sleep Behaviors in Social Networks; URL: https://clinicaltrials.gov/study/NCT02846077; Registration:NCT02846077.