The impact of cyclic alternating pattern on heart rate variability during sleep in healthy young adults

Objective: Cyclic alternating pattern (CAP) consists of arousal-related pha sic events while the complementary condition, non-CAP (NCAP), is characteri zed by a rhythmic background activity, reflecting a condition of stable aro usal, during non-REM sleep. The arousal swings that accompany the appearanc e of CAP on the EEG are associated with transient variations of muscle tone and autonomic activities, including heart rate (HR). The aim of our study was to evaluate HR variability in relation to CAP during non-REM sleep in h ealthy adults. Methods: Ten healthy subjects (mean age = 28.1 years) underwent 8 h polysom nography. HR variations were measured by power spectrum analysis. The ECG s ignals were segmented in correspondence of the different sleep stages and d ifferent CAP conditions. Results: A significant difference between CAP and NCAP conditions was found in low frequency (LF) component (increased in CAP) and high frequency (HF) component (decreased in CAP). LF/HF ratio was increased in CAP. Conclusion: Physiological fluctuations of the EEG arousal level influence c ardiac autonomic activity in normal subjects. The studies on nocturnal vari ation in sympathetic and vagal tone should take in account the microstructu ral sleep changes, other than the conventional polysomnographic parameters. (C) 2000 Elsevier Science ireland Ltd. All rights reserved.