Circadian rhythms of cardiovascular autonomic function: Physiology and clinical implications in neurodegenerative diseases.

Circadian rhythms of blood pressure and heart rate are regulated by a biological clock located in the suprachiasmatic nucleus (SCN) of the hypothalamus, which modulates the autonomic nervous system activity directed to the heart and blood vessels. Humoral mediators released with periodicity induced by the SCN as well as sleep are also important factors. Disruption of physiological cardiovascular circadian rhythms has important clinical implications, as it is associated with increased morbidity and mortality. In this review, firstly we will give an overview on the neuroanatomic and physiologic aspects of cardiovascular circadian rhythms. Secondly we will examine how to assess them in clinical practice. Finally we will discuss certain neurodegenerative diseases in which there is an alteration of these rhythms, such as Parkinson's disease and Alzheimer's disease.