Indirect effect of sleep on abdominal pain through daytime dysfunction in adults with irritable bowel syndrome.

STUDY OBJECTIVES Sleep deficiency, psychological distress, daytime dysfunction and abdominal pain are common in adults with irritable bowel syndrome (IBS). Prior research on individuals with chronic pain has identified the indirect effect of sleep on pain through psychological distress or daytime dysfunction; however, it is less clear in IBS. The purpose of this study was to examine potential indirect effects of sleep on abdominal pain symptoms simultaneously through psychological distress and daytime dysfunction in adults with IBS. METHODS Daily symptoms of nighttime sleep complaints (sleep quality and refreshment), psychological distress, daytime dysfunction (fatigue, sleepiness, and hard to concentrate) and abdominal pain were collected in baseline assessments from two randomized controlled trials of 332 adults (mean age 42 years and 85 % female) with IBS. Structural equation modeling (SEM) was used to examine the global relationships among nighttime sleep complaints, psychological distress, daytime dysfunction and abdominal pain. RESULTS SEM analyses found a strong indirect effect of poor sleep on abdominal pain via daytime dysfunction, but not psychological distress. More than 95% of the total effect of nighttime sleep complaints on abdominal pain is indirect. CONCLUSIONS These findings suggest that the primary impact of nighttime sleep complaints on abdominal pain is indirect. The indirect effect appears primarily through daytime dysfunction. Such understanding provides a potential avenue to optimize personalized and hybrid behavioral interventions for adults with IBS through addressing daytime dysfunction and sleep behaviors. Additional study integrating symptoms with biological markers is warranted to explore the underlying mechanisms accounting for these symptoms.