Circadian Rhythms of Spectral Components of Heart Rate Variability
Circadian rhythms of heart rate variability have been widely studied in recent years. However, most previous reports described such rhythms in terms of normalized units of the low- and high-frequency (LF and HF) spectral components. In this study, we analyzed circadian rhythms of spectral components in absolute units and found unexpected results in normal subjects as well as coronary heart disease (CHD) and congestive heart failure (CHF) patient groups. The results indicate that the notion of sympathovagal balance needs to be re-evaluated