Cardiovascular
Chronotype, rotating night shift work, and cardiovascular disease risk in U.S. women: a prospective cohort study Sina Kianersi* Sina Kianersi Yue Liu Tamar Sofer Isha Agarwal Marta Guasch-Ferré Susan Redline Eva Schernhammer Kathryn Rexrode Tianyi Huang
Introduction: Rotating night shift work is associated with chronic circadian misalignment, and may contribute to cardio-cerebrovascular diseases (CVD) risk. The potential impact of rotating night shift work on CVD may be modified by chronotype, particularly if personal circadian preference and work schedules are mismatched.
Methods: In 2009, 75509 women (avg. age=55 years) with no history of CVD from the Nurses’ Health Study II reported their chronotype. Information on duration of rotating night shift work has been collected biennially since 1989. Participants were prospectively followed for incident CVD (myocardial infarction or stroke), from 2009 until June 2019. We used time-varying Cox proportional hazards models to estimate the HR for CVD according to chronotype and night shift work. We conducted interaction analysis to assess if the association of night shift work with CVD differed by chronotype.
Results: We recorded 754 CVD cases over 673,534 person-years of follow-up. Compared with non-night shift workers, the demographically adjusted HR for CVD was 0.98 (95% CI: 0.82, 1.17) for night shift work of <5 years, and 1.23 (1.01, 1.49) for ≥5 years (P-trend=0.07). Compared with “morning” chronotypes, the demographically adjusted HR for CVD was 1.15 (0.98, 1.35) for “intermediate”, and 1.41 (1.12, 1.76) for “evening” chronotypes (P-trend=0.004). The association comparing ≥5 years vs. no night shift work was stronger in morning chronotypes (HR: 1.45; 95% CI: 1.03, 2.05), which was attenuated after adjusting for traditional CVD risk factors (HR: 1.30; 95% CI: 0.91, 1.84). No association of rotating night work and CVD risk was found in intermediate or evening chronotypes (P for multiplicative interaction=0.09).
Conclusion: Our results suggest that female nurses with a morning chronotype may be more susceptible to the hazardous effects of rotating night shift work on CVD risk.
Funding: R01HL155395, 24POST1188091 (https://doi.org/10.58275/AHA.24POST1188091.pc.gr.190780)