Sleep and the Peripheral Vascular System

Sleep processes involve the body as well as the brain. Blood flow (BF) to different organs matches specific metabolic requirements, which vary with behavioral states of the wake–sleep cycle: wakefulness, non-rapid eye movement (NREM) sleep, and rapid eye movement (REM) sleep. On the other hand, changes in BF are obtained through changes in arterial blood pressure (ABP) and vascular resistance, which, in turn, depend on autonomic output to heart and blood vessels. Autonomic cardiovascular control results fromthe interaction between reflex mechanisms, such as the baroreflex, the chemoreflex, and thermoregulation, and central autonomic commands specific to each sleep state. Thus, sleep-related changes in peripheral circulation depend jointly on changes in organ metabolic rate and on autonomic activity to the heart and blood vessels. The direction and magnitude of sleep-dependent changes in BF to a given vascular bed result from the complex interaction among local systemic reflex, and central autonomic mechanisms. In the following paragraphs, the physiological sleep dependent changes in the cerebral circulation and in extracerebral vascular districts will be reviewed. Whenever possible, the focus will be aimed at translation from animal models to humans and at the mechanisms of the observed circulatory changes. Effects of sleep-related respiratory derangements and sleep loss on the peripheral circulation will also be summarized.