High frequency heart rate variability as predictor of treatment response to cognitive-behavioral therapy for insomnia

Abstract

Introduction: Although cognitive-behavioral therapy for insomnia (CBTI) is the recommended treatment for chronic insomnia, approximately 40% of insomniacs will show residual or recurrent symptoms. To date, there are few reliable predictors of response to CBTI. High-frequency heart rate variability (HRV) has been proposed as a potential index of vulnerability to insomnia. Materials and methods: Individuals with primary insomnia lasting for at least 6 months were recruited into the study. Pre-treatment sleep evaluation included an overnight polysomnography (PSG), 1 week of actigraphy, 1 week of sleep diary, as well as the completion of the Insomnia Severity Index (ISI) and the Pittsburgh Sleep Quality Index (PSQI). At pre-treatment, patients also had their HRV recorded during a resting baseline period and in response to a worry induction task. Subsequently, patients participated in a 6-week group CBTI conducted by a clinical psychologist. At posttreatment, patients completed a second sleep evaluation including polysomnography, actigraphy, sleep diary, and the ISI and PSQI. Results: Participants exhibited a significant reduction in ISI (p < 0.001), PSQI (p < 0.001), PSG-derived sleep efficiency (p < 0.001), sleep diary-derived sleep efficiency, but not on the actigraphyderived sleep efficiency (p = 0.18). Correlations between baseline HRV and the change scores in each sleep parameter were calculated to evaluate whether HRV predicted treatment response to CBTI. Correlations showed that HRV during rest at pre-treatment predicted prospective increases of actigraphy-derived sleep efficiency (R = 0.77), PSG-derived sleep efficiency (R = 0.57), PSG-derived total sleep time (R = 0.76), and a reduction in the PSQI (R = 0.52) after CBTI. Conclusion: High frequency HRV during waking restfulness predicted treatment response to a group-based CBTI among patients with primary insomnia. If these results are replicated, HRV might be used as a potential tool to identify patients who are less likely to respond to CBTI and who may need a more complex treatment regimen. Acknowledgements: This study was supported by the Canada Research Chair Program, the Canadian Institutes of Health Research (CIHR), the Natural Sciences and Engineering Research Council of Canada (NSERC), the Fonds de Recherche du Quebec – Sante (FRQS), the Sleep Research Society Foundation (SRSF), and Concordia University.