title: Correlated and uncorrelated regions in heart-rate fluctuations during sleep.
abstract: Healthy sleep consists of several stages: deep sleep, light sleep, and rapid eye movement (REM) sleep. Here we show that these sleep stages can be characterized and distinguished by correlations of heart rates separated by n beats. Using the detrended fluctuation analysis (DFA) up to fourth order we find that long-range correlations reminiscent to the wake phase are present only in the REM phase. In the non-REM phases, the heart rates are uncorrelated above the typical breathing cycle time, pointing to a random regulation of the heartbeat during non-REM sleep.
authors.affiliation: Institut für Theoretische Physik III, Justus-Liebig-Universität, D-35392 Giessen, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Bunde
authors.forename: S
authors.initials: S
authors.lastname: Havlin
authors.forename: J W
authors.initials: JW
authors.lastname: Kantelhardt
authors.forename: T
authors.initials: T
authors.lastname: Penzel
authors.forename: J H
authors.initials: JH
authors.lastname: Peter
authors.forename: K
authors.initials: K
authors.lastname: Voigt
mesh_terms: D001699:Biometry; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008954:Models, Biological; D010507:Periodicity; D012891:Sleep Apnea Syndromes / Q000503:physiopathology; D012894:Sleep Stages / Q000502:physiology*; D012895:Sleep, REM / Q000502:physiology