Abstract
<jats:p>Background. Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder characterized by abdominal pain and altered bowel habits, involving gut–brain axis dysregulation, psychosocial, and immune mechanisms. Insomnia and sleep disturbances are highly prevalent in IBS and may contribute to symptom burden, but their role remains unclear. Aim. To systematically review the role of insomnia in IBS, focusing on prevalence, symptom severity, mechanisms, and effects of sleep-targeted interventions. Methods. A comprehensive literature search (including PubMed) was conducted for studies published up to 2026. Observational studies, clinical trials, mechanistic studies, and reviews examining the relationship between insomnia and IBS were included. Data on study design, populations, sleep assessment, IBS criteria, and outcomes were extracted. Due to heterogeneity, a qualitative synthesis was performed. Results. Insomnia is more prevalent in IBS patients than controls (37–70%). Greater insomnia severity is associated with increased abdominal pain, bloating, bowel disturbances, and reduced quality of life. Longitudinal and genetic evidence suggests insomnia may be an independent risk factor for IBS onset and exacerbation. Proposed mechanisms include gut–brain axis dysregulation, visceral hypersensitivity, stress response alterations, and immune modulation. Subjective sleep disturbances appear particularly predictive of symptom severity. Behavioral interventions, such as cognitive-behavioral therapy for insomnia (CBT-I), show potential to improve both sleep and IBS symptoms, though current evidence is limited. Conclusions. Insomnia is a common and clinically relevant factor in IBS, acting as both a comorbidity and a modifier of disease severity. Integrating sleep assessment and management into IBS care may improve outcomes. Further large-scale and mechanistic studies are needed to clarify causality and optimize treatment strategies.</jats:p>