Abstract

The Spielman 3P model of insomnia proposes that precipitating factors, such as stress, may contribute to the development of insomnia in good sleepers. Previous research has found that respiratory sinus arrhythmia (RSA) may also interact with stress to exacerbate sleep disturbances, resulting in lower subjective sleep quality in good sleepers. The goal of this study is to examine the association between stress, RSA, and sleep quality among individuals with an insomnia disorder. It is hypothesized that RSA will moderate the association between stress exposure and subjective and objective measures of sleep quality among individuals with primary insomnia. Sixty-two individuals with chronic insomnia participated in this cross-sectional study. They completed the Insomnia Severity Index (ISI) and the Pittsburg Sleep Quality Index (PSQI) to assess subjective sleep quality, as well as a daily stress diary for fourteen consecutive days. Objective sleep efficiency was calculated from polysomnography recording during an overnight study at the laboratory. RSA was collected during a five-minute resting baseline task. Results indicated that RSA moderated the association between daily stress and PSQI and ISI scores, with individuals with lower RSA exhibiting a stronger association between daily stress and worst subjective sleep, compared to those with high RSA. RSA did not moderate the association between average daily stress and sleep efficiency in the present sample. These results suggest that among the subset of patients with low RSA, stress exposure may perpetuate subjective sleep complaints.