In healthy, young individuals, a reduction in cardiovascular output and a shift from sympathetic to parasympathetic (vagal) dominance is observed from wake into stages of nocturnal and daytime sleep. This cardiac autonomic profile, measured by heart rate variability (HRV), has been associated with significant benefits for cardiovascular health. Aging is associated with decreased nighttime sleep quality and lower parasympathetic activity during both sleep and resting. However, it is not known whether age-related dampening of HRV extends to daytime sleep, diminishing the cardiovascular benefits of naps in the elderly. Here, we investigated this question by comparing the autonomic activity profile between young and older healthy adults during a daytime nap and a similar period of wakefulness (quiet wake; QW). For each condition, from the electrocardiogram (ECG), we obtained beat-to-beat HRV intervals (RR), root mean square of successive differences between adjacent heart-beat-intervals (RMSSD), high-frequency (HF), low-frequency (LF) power, and total power (TP), HF normalized units (HFnu), and the LF/HF ratio. As previously reported, young subjects showed a parasympathetic dominance during NREM, compared with REM, prenap rest, and WASO. Moreover, older, compared to younger, adults showed significantly lower vagally mediated HRV (measured by RMSSD, HF, HFnu) during NREM. Interestingly, however, no age-related differences were detected during prenap rest or QW. Altogether, our findings suggest a sleep-specific reduction in parasympathetic modulation that is unique to NREM sleep in older adults.
|State||Published - Jul 2021|
Bibliographical noteFunding Information:
This work was supported by the National Institutes of Health R01 (AG046646) and (AG061355). P.C. analyzed data and wrote the paper; S.C.M, L.N.W., and N.S. designed the study; L.N.W. and N.S. performed research; and S.C.M. supervised research. S.C.M, L.N.W., and N.S. edited the paper.
© 2020 The Authors. Psychophysiology published by Wiley Periodicals LLC on behalf of Society for Psychophysiological Research
- autonomic activity
- heart rate variability
ASJC Scopus subject areas
- Neuroscience (all)
- Neuropsychology and Physiological Psychology
- Experimental and Cognitive Psychology
- Endocrine and Autonomic Systems
- Developmental Neuroscience
- Cognitive Neuroscience
- Biological Psychiatry