News & Technology
Blood Pressure’s Internally Driven Daily Rhythm Unlikely To Be Linked To Morning Heart Attacks
American Heart Association Rapid Access Journal Report: The internally‐driven daily cycle of blood pressure changes doesn’t appear to be linked to the known increase in morning heart attacks, according to a study in Circulation Research: Journal of the American Heart Association.
Researchers sought to identify the role of the internal human body clock in the daily rise and fall in blood pressure. In the study, three groups of volun‐ teers showed an internal daily blood pressure variation with a peak at around 9 p.m. — independent of changes in activity and other behav‐ ioral influences that can affect blood pressure.
Increased blood pressure is a major risk factor for adverse cardiovascular events. However, the study revealed that the internal blood pressure cycle resulted in the lowest blood pressure occurring in the late morning. This unexpected finding indicates that blood pressure’s internal circadian rhythm — a cycle of about 24 hours that occurs in many biological process‐ es — is unlikely to be linked to the well‐ documented morning peak in heart events or strokes, said Steven A. Shea, Ph.D., lead author of the study and associate professor of medicine at Harvard Medical School in Boston, Mass.
“We used three complementary experimental protocols and three dif‐ ferent groups and found essentially the same results,” Shea said. “That means we’re dealing with something very robust.”
Shea and his colleagues randomized 28 volunteers without hypertension to three multi‐day in‐laboratoryprotocols. Before the study, participants main‐ tained a regular sleep‐wake schedule at home (16 hours of scheduled wakeful‐
12 EMS PRO Magazine
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