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Daily Blood Pressure Rhythm Not Linked to Morning Heart Attacks

April 7, 2011



An article in Circulation Research: Journal of the American Heart Association reports that blood pressure is influenced by the human circadian clock independent of the individual's environment or behavior.  The rhythm is not likely connected to a known increase in morning heart attacks because study participants' blood pressure actually peaked at 9pm and was lowest in the late morning.

The study involved 28 healthy volunteers who spent time in the sleep lab for either a 38-hour constant routine with constant body posture, a 196-hour forced desynchrony pattern of recurring 28-hour days, or 240-hour forced desynchrony with recurring 20-hour days. Volunteers under the different schedules still had almost identical internal blood pressure cycles with a peak at night and dip in the morning.

The reason for the spike in morning heart attacks is still not known, but the team hopes to expand the study to people with varying levels of cardiovascular disease risk.

Related Links
Download the article from Circulation Research (PDF)
Press release from Brigham and Women's Hospital


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