Scientists discover why heart attack risk peaks in the early hours
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Posted on Nov 12, 2008, 4 a.m.
By Rich Hurd
Researchers have made a discovery that may help to explain why the risk of heart attack and stroke is at its greatest in the early hours of the morning.
Researchers have made a discovery that may help to explain why the risk of heart attack and stroke is at its greatest in the early hours of the morning.
Dr Ibhar Al Mheid and colleagues from Emory University drew blood from 12 healthy middle-aged volunteers every four hours for 24-hours in order to investigate daily fluctuations in the activity of endothelial progenitor cells (EPCs), stem cells that replace the endothelial cells which line blood vessels. Results showed that the number of EPCs peaks at 8 p.m., whilst the ability of blood vessels to relax and the activity of EPCs both peak at midnight. The activity of EPCs then plummets to its lowest in the early hours of the morning.
“The lining of our vessels appears to function better at night than in the day. Endothelial function is particularly depressed in the early morning hours,” explained Dr Mheid in a news release. He believes that EPC activity and endothelial function is controlled by a circadian timer in the brain.
News release: Daily rhythms in blood vessels may explain morning peak in heart attacks. Emory University. November 10th 2008.
