Autonomic regulation of cardiac function during sleep in patients with irritable bowel syndrome

OBJECTIVE: Several studies have provided evidence of abnormal autonomic act ivity in irritable bowel syndrome (IBS), suggesting that abnormal central n ervous system-autonomic nervous system arousal mechanisms may be part of it s pathophysiology. The goal was to investigate cardiac sympatho-vagal balan ce during waking and the different stages of sleep using heart rate variabi lity analysis in IBS patients compared to healthy controls. METHODS: A total of 15 IBS patients (13 female, two male, mean age 34.9 +/- 2.1 yr) and 15 controls (13 female, two male, mean age 36.2 +/- 2.3 yr) we re studied during 1 h of pre-sleep quiet waking and during seven-hours of s leep. Polysomnography was used for the determination of state of consciousn ess. Electrocardiography provided the beat-to-beat intervals, which were th en subjected to spectral analysis for determination of the percentage of en ergy in the low and high frequency bands, respectively. The low frequency/ high frequency band ratio was also calculated. For each subject, heart rate variability analysis was performed using 15-min segments of waking, non-ra pid eye movement sleep, and rapid eye movement sleep. RESULTS: The low frequency band power was significantly greater in IBS pati ents during waking. No group differences were found in high frequency band power during any state. The low frequency to high frequency band ratio was significantly greater in IBS patients during rapid eye movement sleep. CONCLUSIONS: IBS patients have greater sympathetic activity during waking a nd greater overall sympathetic dominance during rapid eye movement sleep. T hese results support the presence of autonomic abnormalities in patients wi th IBS. The possibility is discussed that sympathetic dominance during rapi d eye movement sleep may play a role in sensitizing the gut to waking stimu lation. (Am J Gastroenterol 2000;95: 2865-2871. (C) 2000 by Am. Coll. of Ga stroenterology).