0395 Shift Work and Sleep Health: Findings from a Sleep Study in the Nurses’ Health Study 3

Abstract Introduction Shift work, common in essential occupations such as nursing, can contribute to poor sleep health and circadian disruption. Comprehensive evidence linking shift-work type to subjective and objective multidimensional sleep health remains limited. Methods In a recent sleep study (2023–2025) within the Nurses’ Health Study 3, we analyzed 946 (98% female) participants who reported their current shift work status in the past four weeks. Fitbit-measured within-person mean total sleep duration and its standard deviation (SD; reflecting irregular sleep duration), in hours, were calculated over a median of 15.5 days per participant (range: 7–82). Participants also completed a sleep questionnaire, including self-reported workday/non-workday sleep duration, insomnia symptoms (Women’s Health Initiative Insomnia Rating Scale, WHIIRS), chronotype (Morningness–Eveningness Questionnaire, rMEQ), and sleep medication use. We used linear and modified Poisson regression to evaluate the cross-sectional associations between current shift work status and sleep health outcomes, adjusted for age, sex, race, and full-time employment status. Results Overall, 32% of participants reported working some type of non-day shift: 11% mixed, 8% early morning, 6% evening, 5% night, and 3% on-call shifts. Shift workers had slightly lower mean rMEQ scores than non-shift workers (p< 0.0001), indicating greater eveningness. Fitbit-measured mean sleep duration was shorter comparing all shift-working groups with non-shift workers, with significant differences for on-call (β: -0.53, 95% CI: -0.97, -0.09) and mixed shift workers (β: -0.32, 95% CI: -0.55, -0.09). Self-reported sleep duration was shorter for shift workers compared with non-shift workers, particularly night-shift workers on workdays (β: –0.99, 95% CI: –1.29, –0.69). Sleep duration irregularity was higher for all shift-working groups compared with non-shift workers, with night-shift workers showing the greatest difference (β: 1.02; 95% CI: 0.83, 1.21). Compared with non-shift workers, sleep medication use was higher among night shift workers (prevalence ratio[PR]: 1.59, 95% CI: 1.21, 2.08), while worse insomnia symptoms (WHIIRS>10) were more prevalent among early morning shift workers (PR: 1.20, 95% CI: 0.94, 1.52). Conclusion Among middle-aged nurses, shift work was adversely associated with several aspects of sleep health. Different shift types were associated with distinct sleep health dimensions, suggesting that health outcomes may also vary by shift type. Support (if any) 24POST1188091, R01HL155395, ZIAAG000530