Kathryn J Reid, Jia Weng, Alberto R Ramos, Phyllis C Zee, Martha Daviglus, Yasmin Mossavar-Rahmani, Daniela Sotres-Alvarez, Linda C Gallo, Diana A Chirinos, Sanjay R Patel

To describe sleep characteristics of shift workers compared to day workers from the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) Sueño ancillary study, and test the hypothesis that shift work is associated with shorter sleep duration, worse sleep quality, greater sleep variability and other sleep/health related factors. Employed adults (N=1,253, mean age 46.3 years, 36.3% male) from the Sueño study were included. Measures of sleep duration, timing, regularity and continuity were calculated from 7-days of wrist-activity monitoring. Participants provided information on demographics, employment, work schedule (day, afternoon, night, split, irregular and rotating), sleepiness, depressive symptoms, medications, caffeine, and alcohol use. Survey linear regression adjusting for age, sex, background, site, number of jobs, and work hours were used. In age and sex-adjusted models, all shift work schedules were associated with delayed sleep timing. Night and irregular schedules were associated with shorter sleep duration, greater napping, and greater variability of sleep. Afternoon and rotating shifts were associated with lower sleep regularity. In fully adjusted models night and irregular schedules remained associated with shorter sleep duration, later sleep midpoint, and greater variability in sleep measures compared to day schedules. Split schedules were associated with, less time in bed, less sleep fragmentation, and less wake during the sleep period than day schedules. Work schedule significantly impacts sleep-wake with substantial differences between day work and other types of schedule. Detailed assessment of work schedule type not just night shift should be considered as an important covariate when examining the association between sleep and health outcomes.