Associations of Long‐Term Night Shift Work With Incident Irritable Bowel Syndrome: A Population‐Based Cohort Study

ABSTRACT Background and Aim To explore the impact of long‐term night shift work on the incidence of irritable bowel syndrome (IBS) and the underlying mechanism. Methods This cohort study included 239 760 participants who were in paid employment or self‐employed from the UK Biobank. The start date refers to the date when a participant joined the cohort between 2006 and 2010, whereas the end of follow‐up was December 31, 2021. In‐depth lifetime employment information was used to calculate the duration and frequency of night shifts. Low‐grade inflammation index (INFLA score) was calculated from five circulating inflammatory biomarkers. Cox proportional hazard models were used to estimate the relationships between long‐term night shifts and IBS risk. Results An increasing trend of IBS incidence was observed from day workers to regular night shift workers. Compared to day workers, rarely/some night shift workers (HR 1.097, 95% CI 1.007–1.195) and usual/permanent night shift workers (HR 1.213, 95% CI 1.046–1.407) had a higher risk of IBS. INFLA score significantly mediated this association (mediation proportion 3.6%, p < 0.05). Workers with a longer duration (≥ 3 years) (HR 1.241, 95% CI 1.073–1.436) and a higher frequency of night shifts (> 7 shifts/month) (HR 1.248, 95% CI 1.045–1.491) also showed higher IBS risks. Conclusion Night shift work, longer night shift duration, and higher night shift frequency were associated with higher risks of IBS. The potential underlying mechanism may be heightened low‐grade inflammation.