Cyclic alternating pattern and spectral analysis of heart rate variability during normal sleep

Area of Science:

• Sleep Medicine
• Autonomic Neuroscience
• Pediatric Cardiology

Background:

• Cyclic alternating pattern (CAP) represents natural arousal rhythms during non-rapid eye movement (NREM) sleep.
• CAP consists of arousal-related phasic events interrupting NREM sleep's tonic activities.
• Previous studies suggested a link between CAP and autonomic function in young adults via heart rate variability (HRV) analysis.

Purpose of the Study:

• To investigate the effects of CAP on HRV in normal children and adolescents.
• To analyze changes in autonomic nervous system balance during sleep stages with and without CAP.

Main Methods:

• All-night polygraphic recordings were conducted on six healthy children and adolescents (aged 10.0-17.5 years).
• Five-minute epochs from sleep Stage 2 and slow-wave sleep (Stages 3-4) were selected under both CAP and non-CAP (NCAP) conditions.
• Time and frequency domain HRV parameters were calculated from electrocardiographic R-R intervals.

Main Results:

• Significant differences in frequency domain HRV parameters were observed between CAP and NCAP epochs.
• CAP was associated with an increased low-frequency band and low-frequency/high-frequency ratio.
• CAP corresponded to a decreased high-frequency band during both Stage 2 and slow-wave sleep.

Conclusions:

• Physiological arousal fluctuations during sleep, characterized by CAP, induce significant changes in autonomic nervous system balance.
• These findings highlight a subtle but important interplay between sleep architecture and autonomic regulation in pediatric populations.
• CAP influences the sympathetic and vagal components of the autonomic system during sleep in children and adolescents.