Molecular Clock Mechanisms and Circadian Rhythms Intrinsic to the Heart

ircadian rhythms are the external expression of an internal clock mechanism that measures daily time. 1 Periodic environmental cues entrain or set the circadian clocks. The daily light-dark cycle represents the most dominant and potent entraining stimulus in mammals. An entrained clock coordinates physiological events to the 24hour day. Normally, cardiovascular or hemodynamic parameters, such as heart rate and blood pressure, exhibit variations