Cardiac activity during sleep onset
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Updated: Oct 20, 2026

Quantifying Infra-slow Dynamics of Spectral Power and Heart Rate in Sleeping Mice
Published on: August 2, 2017
H J Burgess1, J Kleiman, J Trinder
1Department of Psychology, University of Melbourne, Parkville Victoria, Australia.
Abstract:
Alterations in a number of measures of cardiac activity were examined during sleep onset in 6 participants over 3 experimental nights. Each sleep onset was divided into four consecutive phases: wakefulness, mixed alpha and theta activity, stage 2 NREM sleep with arousals, and stable stage 2 sleep. The variables measured were heart rate (HR), respiratory sinus arrhythmia (RSA), pre-ejection period (PEP) and T-wave amplitude (TWA). Respiration rate (RR) was also measured. HR and RR were lower in stable Stage 2 sleep compared with wakefulness, whereas PEP, TWA and RSA did not change significantly. During the second and third phases of sleep onset, HR decreased at each transition into sleep and increased following each spontaneous arousal. This increase resolved rapidly, with a return to sleep levels by 12 beats after the arousal. HR changes are discussed with reference to RSA, PEP, TWA and the concept of a waking reflex.
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