Fluctuations in autonomic nervous activity during sleep displayed by power spectrum analysis of heart rate variability

• Published in: Neurology Vol. 45; no. 6; p. 1183
• Main Authors: Baharav, A, Kotagal, S, Gibbons, V, Rubin, B K, Pratt, G, Karin, J, Akselrod, S
• Format: Journal Article
• Language: English
• Published: United States 01.06.1995
• Subjects: Adolescent; Autonomic Nervous System - physiology; Child; Fourier Analysis; Heart Rate; Humans; Signal Processing, Computer-Assisted; Sleep - physiology
• ISSN: 0028-3878
• DOI: 10.1212/wnl.45.6.1183

The use of an efficient noninvasive method to investigate the autonomic nervous system and cardiovascular control during sleep. 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. 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. 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. 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.