State-dependent responsiveness of cardiovascular system during sleep and wakefulness

The authors have geometrically investigated the relationship among the state-dependent cardiovascular dynamics during physiological states such as sleep and wakefullness. Here, an impulse response analysis is carried out in order to anatomize the authors´ geometrical results in the temporal domain. As a result, the autonomic regulation is suggested to be firmly functioning during slow wave sleep, while weakened or slightly unstabilized during rapid eye movement sleep. During wakefulness, although the state-dependent characteristics of impulse responses varied from subject to subject, the tendency held within a subject. These results are suggested to provide a microscopic interpretation for the geometrically obtained state-dependency of cardiovascular dynamics during sleep and wakefulness