Journal of gastroenterology and hepatologyJul 12, 2025

Long-Term Night Shift Work Linked to New Cases of Irritable Bowel Syndrome in the General Population

Circadian Biology Weekly Brief ↗PubMed ↗DOI ↗

Updated Apr 6, 2026

Abstract

An increasing trend in irritable bowel syndrome (IBS) incidence is observed among 239,760 participants, with regular night shift workers showing a significantly higher risk.

Regular night shift workers had a higher risk of IBS compared to day workers, with hazard ratios of 1.213 for usual/permanent night shift workers.
Rarely/some night shift workers also showed increased IBS risk with a hazard ratio of 1.097 compared to day workers.
A longer duration of night shift work (≥ 3 years) was associated with an elevated IBS risk, with a hazard ratio of 1.241.
A higher frequency of night shifts (> 7 shifts/month) corresponded to an increased IBS risk, with a hazard ratio of 1.248.
Low-grade inflammation, indicated by the INFLA score, significantly mediated the relationship between night shift work and IBS.

Simplified

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.

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Long-Term Night Shift Work Linked to New Cases of Irritable Bowel Syndrome in the General Population

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