<p>Changes in Heart Rate Variability and Baroreflex Sensitivity During Daytime Naps</p>

Abstract

Background and Objectives: Changes in autonomic cardiac activity during night sleep are well documented. However, there is limited information regarding changes in the autonomic cardiac profile during daytime naps. Heart rate variability (HRV) and baroreflex sensitivity (BRS) are reliable measures of autonomic cardiac activity. The purpose of this study was to determine the changes in HRV and BRS during daytime naps in healthy men. Methods: This was a cross-sectional study of 25 healthy men. Polysomnographic recording with electrocardiogram monitoring was conducted for all volunteers during a 50-80 min nap between 3.30 pm and 5.30 pm. Five-minute segments during pre-nap wakefulness, non-rapid eye movement (NREM) sleep stages (N1, N2, and N3), rapid eye movement (REM) sleep stage, and post-nap wakefulness were used to measure changes in the variation in HRV parameters, including inter-beat interval (RR-interval), total spectral power (TP), highfrequency power (HF), low-frequency power (LF), and low frequency/high-frequency ratio (LF/HF). BRS was also measured for 10 min during pre-and post-nap wakefulness using finger arterial pressure measurement (Finometer Pro ®). Results: HRV increased significantly during NREM sleep compared with that during prenap wakefulness (p < 0.05), as reflected by RR-interval prolongation, higher HF, and increased HF nu (normalized units). Furthermore, there was a parallel reduction in TP, LF, and LF/HF ratio during NREM sleep, indicating parasympathetic predominance over cardiac autonomic activity. HF and HF nu were significantly reduced during REM sleep compared with that during NREM sleep (p < 0.05). BRS did not show significant differences between pre-and post-nap wakefulness. Conclusion: We observed a progressive increase in parasympathetic activity during daytime sleep as NREM sleep deepened compared with that during wakefulness and REM sleep. Daytime nap may have a favorable cardiovascular impact.

Association of nocturnal sleep duration and midday napping with subjective poor hearing among middle-aged and older adults in China

“…However, several experimental studies accounted for its positive influence on unhealthy adverse events. Daytime sleep progressively increased parasympathetic activity as non-rapid eye movement sleep deepened, which could help to recover from hearing-related stress ( 48 , 49 ). Besides, napping contributed to stress-releasing and immune responses as a countermeasure to the detrimental health consequences of sleep debt ( 50 ).…”

Acute relaxation during pregnancy leads to a reduction in maternal electrodermal activity and self-reported stress levels

“…On the basis of a study by Doberenz and colleagues [ 50 , 51 ], SCL and heart rates are known to be lower in sleep than when awake. During the measurement, five women fell asleep (Music: N = 2; Guided Imagery: N = 2, Resting: N = 1), which can lead to a different baseline in SCL and thus to a less significant decrease in SCL compared to women who remained awake for the whole intervention.…”

Surge of Sympathetic Activity during Hyperventilation at the End of Apnea for Patients with Obstructive Sleep Apnea

“…The LF/HF ratio served as an indicator of sympathovagal balance [ 17 ]. In this study, the LF/HF ratio was employed to assess sympathetic activity, as per the methodology outlined in the study by AlQatari et al [ 18 ].…”