Heart rate variability in normal and pathological sleep

Abstract

Sleep is a physiological process involving different biological systems, from molecular to organ level; its integrity is essential for maintaining health and homeostasis in human beings. Although in the past sleep has been considered a state of quiet, experimental and clinical evidences suggest a noteworthy activation of different biological systems during sleep. A key role is played by the autonomic nervous system (ANS), whose modulation regulates cardiovascular functions during sleep onset and different sleep stages. Therefore, an interest on the evaluation of autonomic cardiovascular control in health and disease is growing by means of linear and non-linear heart rate variability (HRV) analyses. The application of classical tools for ANS analysis, such as HRV during physiological sleep, showed that the rapid eye movement (REM) stage is characterized by a likely sympathetic predominance associated with a vagal withdrawal, while the opposite trend is observed during non-REM sleep. More recently, the use of non-linear tools, such as entropy-derived indices, have provided new insight on the cardiac autonomic regulation, revealing for instance changes in the cardiovascular complexity during REM sleep, supporting the hypothesis of a reduced capability of the cardiovascular system to deal with stress challenges. Interestingly, different HRV tools have been applied to characterize autonomic cardiac control in different pathological conditions, from neurological sleep disorders to sleep disordered breathing (SDB). In summary, linear and non-linear analysis of HRV are reliable approaches to assess changes of autonomic cardiac modulation during sleep both in health and diseases. The use of these tools could provide important information of clinical and prognostic relevance.

Heart rate variability in insomnia patients: A critical review of the literature

“…(20) However, the extant research literature has not been able to replicate these findings with comparable detail and instead yielded somewhat inconsistent, divergent findings. (21) Whilst two reviews examining HRV, sleep and sleep disorders have been published previously they did not systematically synthesise the findings of the insomnia -HRV literature and we were aware of additional studies that were not included (5,13). Therefore, the aim of this review was to identify all HEART RATE VARIABILITY IN INSOMNIA PATIENTS …”

“…(5, 9, 13) Accordingly, the research focus has shifted to investigating the associations between HRV, sleep disorders and their subsequent comorbidities and the incorporation of non-traditional HRV techniques. (5,13,14) Given the interplay between HRV and cardiac autonomic activity, the use of HRV in insomnia research may assist further investigation into the pathophysiology and potential health impacts of insomnia. Hyperarousal has been defined as 'a state of increased arousal at the physiological, cortical, cognitive or emotional level' (15) and hypothesised to contribute to the development, maintenance and 24-hour systemic sequelae of insomnia.…”

Correntropy-Based Pulse Rate Variability Analysis in Children with Sleep Disordered Breathing

“…Several studies have shown that OSA affects the normal variation of heart rate and that both HRV [5,7,15,31] and PRV [9,32] might help identifying OSA events. Some studies have suggested that certain nonlinear measures of HRV are better predictors of future adverse events in various patient groups than the standard linear measures [13].…”

“…Thus, analysis of heart rate variability (HRV) has been investigated as a possible predictor of OSA [5][6][7]. Studies have shown that OSA affects the normal variation of heart rate and that both HRV and pulse rate variability (PRV), a surrogate measure of HRV estimated from the photoplethysmogram (PPG) [8], may assist with the identification of OSA events [9,10].…”

Chronic Obstructive Pulmonary Disease and Sleep Quality

“…REM sleep has a parasympathetically medicated tonic component and sympathetically mediated phasic component. The phasic component of REM sleep is characterized by skeletal muscle twitches, increased heart rate variability, pupil dilation, and increased respiratory rate [16][17][18]. During NREM sleep, the metabolic demand of the brain decreases and the blood flow throughout the entire brain progressively decreases [19][20][21].…”