title: Correlation between electroencephalography and heart rate variability during sleep.
abstract: It is known that autonomic nervous activities change in correspondence with sleep stages. However, the characteristics of continuous fluctuations in nocturnal autonomic nerve tone have not been clarified in detail. The study aimed to determine the possible correlation between the electroencephalogram (EEG) and autonomic nervous activities, and to clarify in detail the nocturnal fluctuations in autonomic nerve activities. Overnight EEGs and electrocardiograms of seven healthy males were obtained. These EEGs were analyzed by fast Fourier transformation algorithm to extract delta, sigma and beta power. Heart rate and heart rate variability (HRV) were calculated in consecutive 5-min epochs. The HRV indices of low frequency (LF), high frequency (HF) and LF/HF ratio were calculated from the spectral analysis of R-R intervals. The sleep stages were manually scored according to Rechtschaffen and Kales' criteria. Low frequency and LF/HF were significantly lower during non-rapid eye movement (NREM) than REM, and were lower in stages 3 and 4 than in stages 1 and 2. Furthermore, delta EEG showed inverse correlations with LF (r = - 0.44, P < 0.001) and LF/HF (r = - 0.41, P < 0.001). In contrast, HF differed neither between REM and NREM nor among NREM sleep stages. Detailed analysis revealed that correlation was evident from the first to third NREM, but not in the fourth and fifth NREM. Delta EEG power showed negative correlations with LF and LF/HF, suggesting that sympathetic nervous activities continuously fluctuate in accordance with sleep deepening and lightening.
authors.affiliation: Biofunctional Informatics, Graduate School of Allied Health Sciences, Tokyo Medical and Dental University, Department of Sleep Disorders Research, Tokyo Japan.
authors.forename: Mina
authors.initials: M
authors.lastname: Ako
authors.forename: Tokuhiro
authors.initials: T
authors.lastname: Kawara
authors.forename: Sunao
authors.initials: S
authors.lastname: Uchida
authors.forename: Shinichi
authors.initials: S
authors.lastname: Miyazaki
authors.forename: Kyoko
authors.initials: K
authors.lastname: Nishihara
authors.forename: Junko
authors.initials: J
authors.lastname: Mukai
authors.forename: Kenzo
authors.initials: K
authors.lastname: Hirao
authors.forename: Junya
authors.initials: J
authors.lastname: Ako
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Okubo
mesh_terms: D000328:Adult; D003700:Delta Rhythm; D004562:Electrocardiography; D004569:Electroencephalography; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D017286:Polysomnography; D012895:Sleep, REM / Q000502:physiology*