title: Scale-invariant aspects of cardiac dynamics across sleep stages and circadian phases.
abstract: We review recent attempts to understand the influence of sleep and wake states, sleep-stage transitions during sleep and the endogenous circadian rhythms on the neuroautonomic regulation of cardiac dynamics as represented by the scale-invariant organization of heartbeat fluctuations. We find that the probability distribution, the long-range temporal correlations as well as the nonlinear properties of the heartbeat fluctuations are significantly altered with transition from sleep to wake state, across sleep-stages and circadian phases. These sleep and circadian mediated changes in cardiac dynamics occur simultaneously over a broad range of time scales, suggesting a more complex then previously known interaction between the neural systems of sleep and circadian regulation with the neuroautonomic cardiac control, beyond rhythmic modulation at a characteristic time scale.
authors.affiliation: Dept. of Physics, Boston University, Boston, MA 02215, USA.
authors.forename: Plamen Ch
authors.initials: PCh
authors.lastname: Ivanov
mesh_terms: D000328:Adult; D001683:Biological Clocks / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D003198:Computer Simulation; D005260:Female; D006321:Heart / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D009991:Oscillometry / Q000379:methods*; D012894:Sleep Stages / Q000502:physiology*