Correlated and uncorrelated regions in heart-rate fluctuations during sleep.
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.
Bunde
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Institut für Theoretische Physik III, Justus-Liebig-Universität, D-35392 Giessen, Germany.
Havlin
S
S
Kantelhardt
J W
JW
Penzel
T
T
Peter
J H
JH
Voigt
K
K
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