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.