Heart Rhythm Control During Sleep

Abstract

Heart rate (HR) rhanRcs during sleep were analyzed, with the aid of a minicomputer, for a group of 20 healthy subjects. In stages 1, 2, 3, and 4, HR decreased against a background of increasing respiratory arrhythmia. REM sleep was characterized by increased HR and decreased respiratory arrhythmia. HR changes during sleep were dependent on the subject's initial autonomic HR control level. The evidence from 3 healthy subjects, who were studied under baseline conditions, propranolol (a sympatholytic agent), atropine (a parasympathetic depressant), and propranolol plus atropine, showed that the HR decrease during stages I, 2, 3, and 4 is caused by augmented parasympathetic input. The HR increase during REM sleep is due to a reduction in parasympathetic control. The sympathetic input remains relatively constant throughout all stages of sleep, except for its decrease during stage 1.DESCRIPTORS: Heart rhythm, Non-REM sleep, REM sleep, Sympathetic-parasympathetic control, Beta-adrenoblockade, Atropine. A relationship between sleep and blood pressure and heart rate (HR) has been known since the pioneering work by MacWilliams (1923). Brooks et al. (1956) described a significant increase in HR upon transition from "deep" to more "sujjerficial" sleep. Snyder, Hobson, Morrison, and Goldfrank (1964) observed an increase and decrease in HR. in rapid eye movement (REM) and non-REM sleep, respectively. According to Aldredge and Welch (1973), HR is significantly higher in REM sleep as compared with stages 2, 3, and 4, and HR variability decreases with increasing depth of sleep. Nishimuta, Masuda, Uchino, and Oomori (1978) observed large HR fluctuations during REM sleep and stage 1, small fluctuations during stages 3 and 4, and a combination of both during stage 2. A number of reports have appeared presenting evidence for decreased HR during stages I through 4 and increased HR during REM sleep in healthy subjects

Sleep-related sympathovagal imbalance in SHR

“…This algorithm was modified to achieve an automatic, continuous, and multisignal analysis to meet the needs of sleep studies. With the use of such techniques, our previous studies demonstrated that QS was accompanied by an intense vagal function but an attenuated sympathetic function compared with AW (28,29), and these findings were compatible with earlier reports (1,30). The changes of sleep-related autonomic functions associated with spontaneous hypertension, however, have not yet been systemically investigated.…”

“…The data under sleep, however, have been relatively less reported and may be different from those under anesthesia or AW. It has been reported that sleep triggers a series of changes in autonomic functions (1,(28)(29)(30), and the changes may be very vigorous (28,29). Because most of the previous studies regarding the ANS have been carried out for a relatively short time during the daytime, which is the time when rats sleep, it is in fact difficult to quantify the autonomic changes accurately without a classification of sleep-wake states.…”

A prominent role for amygdaloid complexes in the Variability in Heart Rate (VHR) during Rapid Eye Movement (REM) sleep relative to wakefulness

“…The acquisition times for wakefulness, REMS and NREMS largely overlapped. Furthermore, a circadian factor is probably minor because VHR is highly sleep stage dependent (Zemaityte et al, 1984;Raetz et al, 1991;Vanoli et al, 1995;Pivik et al, 1996;Brandenberger et al, 2001;Viola et al, 2002). For instance, individual profiles revealed abrupt HR increases in each transition from deeper sleep to lighter sleep or awakening (Viola et al, 2002).…”

Vigilance, alertness, or sustained attention: physiological basis and measurement

“…There is a decrease in heart rate and this decrease may be seen even prior to onset of stage 1 (Pivik and Busby, 1996) although the heart rate changes during drowsiness are not great (Torsvall and Akerstedt, 1987;Welch and Richardson, 1973). The heart rate decrease during the sleep onset period appears to relate to decreased sympathetic and increased parasympathetic tone (Zemaityte and Varoneckas, 1984). There are also physiologic changes in respiration.…”