Gastrointestinal symptom prevalence and severity among night shift workers: a cross-sectional study

Approximately 25% of the global workforce engages in night shift work (1) , characterised by non-standard hours outside the conventional 6:00am to 6:00pm window. This irregular wakefulness and pattern of mealtimes disrupt circadian rhythms, which are essential for regulating physiological and behavioural functions, including digestion, nutrient absorption, motility, gut microbiome, and hormone secretion (2) . Despite some evidence suggesting a link between shift work and increased gastrointestinal (GI) issues (3) , comprehensive data on the prevalence and impact of GI disorders among night shift workers remains limited. This cross-sectional study aimed to assess the prevalence of functional GI disorders (e.g., irritable bowel syndrome, functional dyspepsia), their impact on well-being, and contributing factors among night shift workers across various industries. Participants were adults based in Australia or the United Kingdom, and were currently employed in regular night shift work. Participants with previously diagnosed GI disease (e.g., malignancy, inflammatory bowel disease), previous surgery of the GI tract, or were pregnant/lactating were excluded. An online survey was administered via REDCap, utilising validated tools to assess the self-reported presence and severity of upper and lower GI symptoms, quality of life, psychological symptoms, and dietary habits. A total of 392 participants completed the survey (median age 48 (16) years; 52% from Australia, 48% from UK). Results revealed that 21.27% of participants met the Rome IV diagnostic criteria for irritable bowel syndrome, 30.36% for functional dyspepsia, and 24.49% for both disorders. Rotating shift workers reported an increased symptom severity when working night shifts compared to fixed night shift workers (p = 0.003). Of concern, 16.33% of participants considered quitting their job due to the impact of their GI symptoms. Quality of life was reduced in the participants meeting criteria for gut disorders compared to those who did not, with these participants reporting food avoidance, negative body image, and ongoing concerns about their general health (all p < 0.001). For the participants meeting gut disorder diagnostic criteria, they also reported elevated scores on the depression anxiety stress scale (p = 0.001) and GI-specific anxiety (p < 0.001), characterised by constant worry about abdominal sensations and discomfort. 81% of the participants who met criteria for GI disorder diagnosis self-managed their symptoms through dietary modifications, such as the low FODMAP diet or the use of supplements including probiotics and peppermint oil. In conclusion, night shift workers experience substantially higher rates of irritable bowel syndrome and functional dyspepsia than those reported in the general population (4.1% and 7.2% respectively, worldwide) (4) . This study underscores the substantial burden of GI disorders among night shift workers, and highlights the need for further research to understand underlying mechanisms and develop effective symptom management strategies.