Circadian behavior of cardiovascular variability

Abstract

The autonomous nervous system is modulated by the sleep-wake cycle and the circadian system at the same time. In order to investigate the separate circadian influence on noninvasive parameters of the cardiovascular variability which could reflect the state of the autonomic tone, we applied a 40-hours constant routine protocol on twelve healthy young volunteers. During that period continuous multi-channel recordings of EKG, EEG, EOG, EMG and respiration were performed. Out of the EKG, sampled with 512 Hz, time domain as well as frequency domain heart rate variability parameters were calculated time-variant in 15-min bins. Descriptive analysis of results revealed a clear circadian modulation of the parameters of the cardiovascular variability. Additionally effects induced by the experimental setting were observed. The findings could make contribution in the design of a noninvasive autonomic state index measure which could be used in patients as well as for daily work life conditions. © 2009 Springer-Verlag.