Heart Rate and Heart Rate Variability Modification in Chronic Insomnia Patients

Chronic insomnia is highly prevalent in the general population, provoking personal distress and
increased risk for psychiatric and medical disorders. Autonomic hyper-arousal could be a pathogenic
mechanismof chronic primary insomnia. The aim of this study was to investigate autonomic activity
in patients with chronic primary insomnia by means of heart rate variability (HRV) analysis.
Eighty-five consecutive patients affected by chronic primary insomnia were enrolled (38 men and
47 women; mean age: 53.2 ˙ 13.6). Patients were compared with a control group composed of 55
healthy participants matched for age and gender (23 men and 32 women; mean age: 54.2 ˙ 13.9).
Patients underwent an insomnia study protocol that included subjective sleep evaluation, psychometric
measures, and home-based polysomnography with evaluation of HRV in wake before sleep,
in all sleep stages, and in wake after final awakening. Patients showed modifications of heart rate and HRV parameters, consistent with increased sympathetic activity, while awake before sleep and
during Stage-2 non-REM sleep. No significant differences between insomniacs and controls could
be detected during slow-wave sleep, REM sleep, and post-sleep wake. These results are consistent
with the hypothesis that autonomic hyper-arousal is a major pathogenic mechanism in primary
insomnia, and confirm that this condition is associated with an increased cardiovascular risk.