Polysomnographic and Actigraphic Evidence of Sleep Fragmentation in Patients with Irritable Bowel Syndrome

Study Objective: To characterize the function and quality of sleep in patients with irritable bowel syndrome (IBS).

Design: A prospective study with a historic comparison group.

Setting: A regional hospital that also serves as a tertiary referral center.

Patients: Eighteen patients with IBS and a comparison group of 20 matched adults with mild benign snoring.

Interventions: A polysomnography study and a wrist actigraphy study.

Measurements: All subjects underwent sleep studies and completed self-report questionnaires (IBS severity, psychosocial variables, sleep function, and Epworth Sleepiness Scale). Fourteen IBS and 11 comparison patients underwent actigraphy.

Results: The IBS patients had more than 70% less slow-wave stage sleep (4.5 +/- 7.3% vs 19.3 +/- 12.9%; P = 0.006), compensated by increased stage 2 sleep (72.2 +/- 6.6% vs 60.1 +/- 16.8%; P = 0.01). The IBS group had significant sleep fragmentation with a significantly higher arousal and awakening index (P < 0.001), a longer wake period after sleep onset (P = 0.02), and more downward shifts to lighter sleep stages (P = 0.01). The 4-night actigraphy study supported the polysomnography findings. The sleep fragmentation index was significantly higher (P = 0.008) in the IBS group. The IBS patients reported greater daytime sleepiness (9.0 +/- 4.8 vs 6.4 +/- 4.8, Epworth Sleepiness Scale score, P < 0.01) and greater impairment in quality of life, which correlated significantly with the sleep fragmentation indexes. The difference between the groups was not due to differences in baseline anxiety/depression levels.

Conclusions: Patients with IBS have impaired sleep quality, reduced slow-wave sleep activity, and significant sleep fragmentation. The cause-and-effect relationship of these findings with patients' daytime symptoms should be studied further.