0349 Circadian Patterns of Blood Pressure Differ Between Retired Night Shift Workers and Retired Day Workers

Abstract

Abstract Introduction Approximately 15% of full-time employees in the U.S. work outside the traditional daytime schedule. These individuals exhibit circadian rhythm abnormalities and increased rates of cardiovascular disease compared to day shift workers. Altered circadian patterns of cardiovascular function may persist into retirement even after returning to a normal nocturnal sleep schedule, and may contribute to the elevated cardiovascular disease burden among retired night shift workers. The purpose of this study was to determine whether circadian rhythms of cardiovascular indicators differed between retired night shift workers and retired day workers. Methods Participants (N = 72, 53% females, 83% non-Hispanic White, mean age: 68.66 years) were 33 retired night shift workers and 39 retired day workers who completed a 60-hour sleep/circadian laboratory assessment. Blood pressure and heart rate were assessed hourly during a 24-hour constant routine protocol. Multilevel cosinor analysis estimated group differences in circadian rhythms of systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), and heart rate (HR). Covariates included age, sex, race, education, and body mass index. Results The 24-hour pattern of DBP (bsine*shiftwork = 1.47, [95% CI: 0.58, 2.35], p = 0.002) and MAP (bsine*shiftwork = 1.38, [95% CI: 0.28, 2.50], p = 0.015) differed between retired night shift workers and retired day workers. Retired night shift workers displayed a later trough of DBP and MAP compared to retired day workers. No group differences were found for circadian rhythms of SBP or HR. Conclusion Retired night shift workers exhibited altered circadian rhythms of blood pressure, which may indicate a circadian “scarring” of night shift work that persists after a return to normal daytime schedule. Future research should investigate explanations for observed differences and the extent to which chronic alterations in cardiovascular circadian rhythms affect morbidity and mortality. Support R01AG047139, T32HL082610, T32HL07560, UL1TR001857