Endogenous circadian rhythm in human motor activity uncoupled from circadian influences on cardiac dynamics.

ABSTRACT: The endogenous circadian pacemaker influences key physiologic functions, such as body temperature and heart rate, and is normally synchronized with the sleep/wake cycle. Epidemiological studies demonstrate a 24-h pattern in adverse cardiovascular events with a peak at approximately 10 a.m. It is unknown whether this pattern in cardiac risk is caused by a day/night pattern of behaviors, including activity level and/or influences from the internal circadian pacemaker. We recently found that a scaling index of cardiac vulnerability has an endogenous circadian peak at the circadian phase corresponding to approximately 10 a.m., which conceivably could contribute to the morning peak in cardiac risk. Here, we test whether this endogenous circadian influence on cardiac dynamics is caused by circad

SUBMITTER: Ivanov PCh 

PROVIDER: S-EPMC2410066 | biostudies-literature | 2007 Dec

REPOSITORIES: biostudies-literature