Evidence for fractal correlation properties in variations of peripheral arterial tone during REM sleep

I. Dvir, Y. Adler, D. Freimark, P. Lavie

Research output: Contribution to journalArticlepeer-review


Previous studies utilizing detrended fluctuation analysis (DFA) of heart rate variability during sleep revealed a higher fractal exponent during rapid eye movement (REM) sleep than non-REM sleep. The aim of this study was to determine whether the same difference exists in the variations of peripheral arterial tone (PAT). Finger pulse wave measured by a novel plethysmographic technique was monitored during sleep in 12 chronic heart failure patients, 8 heavy snorers, and 12 healthy volunteers. For each subject, at least two 15-min time series were constructed from the interpulse intervals and from pulse wave amplitudes during REM and non-REM sleep. Fractal scaling exponents of both types of time series were significantly higher for REM than non-REM sleep in all groups. In each of the groups and in both sleep stages, the fractal scaling exponents based on pulse wave amplitude were significantly higher than those based on pulse rate variability. A repeat of the analysis for short-, intermediate-, and long-term intervals revealed that the fractallike exponents were evident only in the short- and intermediate-term intervals. Because PAT is a surrogate of sympathetic activation, our results indicate that variations in sympathetic activation during REM sleep have a fractallike behavior.

Original languageEnglish
Pages (from-to)H434-H439
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Issue number1 52-1
StatePublished - 2002


  • Congestive heart failure
  • Detrended fluctuation analysis
  • Heavy snoring


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