title: Fluctuations in autonomic nervous activity during sleep displayed by power spectrum analysis of heart rate variability.
abstract: OBJECTIVE
  The use of an efficient noninvasive method to investigate the autonomic nervous system and cardiovascular control during sleep.
  
  
  BACKGROUND
  Beat-to-beat heart rate variability displays two main components: a low-frequency (LF) one representing sympathetic and parasympathetic influence and a high-frequency (HF) component of parasympathetic origin. Sympathovagal balance can be defined as LF/HF ratio.
  
  
  METHODS
  We reviewed normal, standardly staged all-night polysomnograms from 10 healthy children aged 6 to 17 years. Recorded 256-second traces of heart rate and respiration were sampled. Power spectra of instantaneous heart rate and respiration were computed using a fast Fourier transform method.
  
  
  RESULTS
  The study revealed a decrease in LF during sleep, with minimal values during non-REM slow-wave sleep and elevated levels similar to those of wakefulness during REM. HF increased with sleep onset, reaching maximal values during slow-wave sleep, and behaved as a mirror image of LF. LF/HF ratio displayed changes similar to those in LF.
  
  
  CONCLUSIONS
  The sympathetic predominance that characterizes wakefulness decreases during non-REM sleep, is minimal in slow-wave sleep, and surges toward mean awake levels during REM sleep. The autonomic balance is shifted toward parasympathetic predominance during slow-wave sleep. This noninvasive method used to outline autonomic activity achieves results that are in complete agreement with those obtained with direct invasive tools.
authors.affiliation: Department of Pediatric Pulmonary Medicine, Saint Louis University Health Sciences Center, MO, USA.
authors.forename: A
authors.initials: A
authors.lastname: Baharav
authors.forename: S
authors.initials: S
authors.lastname: Kotagal
authors.forename: V
authors.initials: V
authors.lastname: Gibbons
authors.forename: B K
authors.initials: BK
authors.lastname: Rubin
authors.forename: G
authors.initials: G
authors.lastname: Pratt
authors.forename: J
authors.initials: J
authors.lastname: Karin
authors.forename: S
authors.initials: S
authors.lastname: Akselrod
mesh_terms: D000293:Adolescent; D001341:Autonomic Nervous System / Q000502:physiology*; D002648:Child; D005583:Fourier Analysis; D006339:Heart Rate; D006801:Humans; D012815:Signal Processing, Computer-Assisted; D012890:Sleep / Q000502:physiology*