Cardiovascular regulation and cardiovascular diseases: what can sleep teach us?

Abstract

infarction, ventricular arrhythmias and sudden death, which reach a maximum in the early morning after awakening [3]. Other cardiovascular effects of sleep follow cyclic changes during the night, being associated with the occurrence of specific sleep stages. In fact, physiological sleep is composed by a phase of nonrapid eye movements (NREM), with a predominant parasympathethic tone, followed by a rapid eye movement (REM) phase, with autonomic tone similar to the awake phase. The sequence of NREM/REM phases repeats cyclically, with four or five cycles occurring every night, REM phases appearing longer at the end than at the beginning of sleep. The associated cyclic changes of autonomic tone influence importantly heart rate, blood pressure, cardiac output and peripheral resistance. Circadian variations and cyclic changes in sleep stages probably interact with each other.