Sleep disturbances in the irritable bowel syndrome and functional dyspepsia are independent of psychological distress: a population-based study of 1322 Australians

Background: Psychological distress, strongly associated with functional gastrointestinal disorders (FGIDS), likely plays a central role in the pathophysiology. The role of sleep disturbances in FGIDs is unclear, and an association with psychological factors is uncertain. Aim: To determine whether sleep disturbances are associated with irritable bowel syndrome (IBS) and functional dyspepsia (FD) and if a potential association is explained by psychological distress. Methods: Adult sample randomly selected from a region in New South Wales, Australia in 2015 who returned a follow-up mail survey in 2018 (response rate, 60.5%) that contained questions on IBS, FD, sleep (MOS-Sleep Scale) and psychological distress (Kessler 6 scale). Results: Among this population, 10.4% (95% CI 8.8-12.2) and 17.9% (95% CI 15.9-20.1) met Rome III criteria for IBS and FD, respectively. The prevalence of any sleep disturbance at least most of the time was common, with a significantly higher prevalence in FGID (IBS and/or FD) compared with the remaining population (41.8% vs 32.2%, P = 0.003). The total sleep problem index was significantly higher for IBS (OR = 1.71 [95% CI 1.29-2.27], P < 0.0001) (IBS-diarrhoea predominant and IBS-mixed but not IBS-constipation) and FD (OR = 1.80 [1.43-2.26], P < 0.0001) (both epigastric pain syndrome and postprandial distress syndrome) even after adjusting for age, sex and psychological distress. Conclusion: Both IBS and FD, and most of their major subtypes except IBS-C, are associated with a range of sleep disturbances. These sleep problems do not appear to be explained by psychological factors and may play an independent role in the pathophysiology.