The High Frequency Component of Heart Rate Variability and Delta EEG Power during Sleep in Healthy Women and Women with Irritable Bowel Syndrome

Thesis (Ph.D.)--University of Washington, 2016-06

Background Sleep disturbances are well-documented among persons with irritable bowel syndrome (IBS). Imbalanced autonomic nervous system (ANS) has been proposed to be one of the pathophysiology for IBS. Polysomnography (PSG) is a gold measure for sleep quality and heart rate variability (HRV) is a non-invasive measure of ANS activity. Correlations between HRV parameters and electroencephalogram (EEG) power band have been reported in healthy participants and the correlations are weaker among some patient population, e.g., insomnia. Objective A systematic review was conducted to evaluate the evidence of sleep disturbances in adults with IBS and their relationship with GI symptoms. A secondary data analysis was conducted to investigate the relationship between the high frequency (HF) power of HRV and EEG delta band power in women with IBS compared to healthy control women. Methods A literature search was conducted in PubMed, CINAHL, and PsycINFO using keyword ‘irritable bowel syndrome’ and ‘sleep’. In the second study, HRV and EEG data were recorded using PSG in 20 women with IBS and 20 healthy control women in a sleep laboratory for three consecutive nights. Data from the second night were used for this analysis. The traditional coherence analysis was used to determine the coherence, gain, and phase shift between normalized high frequency (HF) power of HRV and normalized delta band power of EEG in the first four NREM-REM sleep cycles. Results The systematic review showed that sleep disturbances are common in adults with IBS. Sleep discrepancy is found between objective and subjective sleep measures. Some evidence supports the positive association between increased sleep disturbances and exacerbated GI symptoms. In the second study, women with IBS had slightly lower coherence between normalized HF and normalized EEG delta band power but it was not statistically significant; had longer phase shift between HF and delta band power than controls (11.6±4.8 min vs. 6.3±3.0 min). Conclusion Sleep disturbances are common in adults with IBS, which also related to exacerbation of GI symptoms. Based on the coherence analysis, there is evidence of dysfunction in the communication between ANS and CNS in women with IBS.