Nocturnal heart rate variability in patients treated with cognitive–behavioral therapy for insomnia

Objective: Insomnia and reduced heart rate variability (HRV) increase the risk of cardiovascular disease and its precursors; thus, it is important to evaluate whether treatment for insomnia provides cardiovascular safeguards. The present study aimed to evaluate potential cardiovascular benefits of cognitive behavioral therapy for insomnia (CBT-I). Method: The present study included 65 patients treated for chronic insomnia (M 51.8 years, SD 10.0; 66.2% female) at a university hospital. Patients received CBT-I over a 6-week period, and change scores from pre- to posttreatment derived from the Insomnia Severity Index, sleep diary, and polysomnography (PSG) were used as indices of sleep improvement. HRV variables (i.e., low frequency [LF], high frequency [HF], and the ratio of low to high frequency [LF:HF ratio]) were derived for Stage 2 (S2) and rapid-eye movement (REM) sleep at pre- and posttreatment. High HF (i.e., parasympathetic activity) and/or low LF:HF ratio (i.e., sympathovagal balance) were used as indices of HRV improvement. Results: Following therapy, sleep improvements, particularly for sleep onset latency, were related with reduced HF in S2 (r .30, p .05) and in REM (r .36, p .01). A trend was also observed between reduced insomnia symptoms and increased HF in REM (r .21, p .10). Conclusions: Findings suggest that contrary to expectations, sleep improvements following CBT-I were associated with reduced parasympathetic activation and increased sympathovagal balance. Although preliminary, these results raise the question as to whether insomnia treatment might play a role in physiological changes associated with cardiovascular anomalies. Future research is needed to examine the long-term impact of treatment as a preventative tool against insomnia-related morbidity