Impact of night shift work on vascular function in healthy adult workers

Background: Night shift work (NSW) is associated with increased cardiovascular risk, but its impact on vascular function and the role of lifestyle factors in healthy individuals remain unclear. We aimed to compare vascular function between NSW and day workers (DW) and to examine associations with objectively measured lifestyle behaviors. Methods: In this cross-sectional study, 40 healthy adults (20 DW, 20 NSW) underwent assessments of flow-mediated dilation (FMD), brachial–ankle pulse wave velocity (baPWV), and ankle–brachial index (ABI). Physical activity and sleep status were objectively measured using triaxial accelerometry for 7 consecutive days. Group comparisons and correlation analyses were conducted to evaluate the effects of NSW and its association with lifestyle factors. Results: FMD was significantly lower in the NSW group than in the DW group (4.0% vs. 7.0%, P < 0.01), while baPWV and ABI showed no between-group differences. In the overall cohort, FMD was positively correlated with time in bed, total sleep time, and sleep efficiency, and negatively correlated with nocturnal awakening. Subgroup analysis revealed that FMD was associated with sleep quality in DW and with physical activity patterns in NSW. Conclusions: Chronic night shift work is associated with impaired endothelial function in healthy adults, potentially driven by disrupted sleep and reduced physical activity. Early assessment using FMD and targeted behavioral interventions may help preserve vascular health among shift workers. Lay summary: This study shows that healthy adults who regularly work night shifts have poorer blood vessel function than people who only work daytime hours, and that sleep and physical activity patterns may help explain this difference.