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

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.