Posted by Brigham and Women's Hospital December 4, 2013
Have you ever wondered why most heart attacks occur in the morning? According to recent research from Brigham and Women’s Hospital (BWH) and Oregon Health & Science University, it turns out that your body clock may play a contributing role.
“Our findings suggest that the circadian system, the internal body clock, may contribute to the increased risk for cardiovascular events in the morning,” says study author Frank A.J.L. Scheer, PhD, MSc, Director of the Medical Chronobiology Program at BWH.
Your circadian system regulates and coordinates many of your body’s functions, including metabolism. It tells your body when you should sleep and when you should eat. In this particular study, the researchers found that the body clock drives day/night variations in the quantity of a protein known to be a risk factor for heart attacks and ischemic strokes. The protein is called plasminogen activator inhibitor-1 (PAI-1). It inhibits the breakdown of blood clots and, thus, is a major risk factor for blood clotting.
The researchers designed the study so that they could isolate the PAI-1/body clock relationship from any behavioral or environmental factors that typically occur in the morning, such as altered body posture or changes in physical activity. The researchers subsequently found that PAI-1 levels peak at just about the same time as a person normally wakes up – making the morning a risky time for your heart.
The researchers note that their study was focused on healthy adults, and they look forward to future research that examines the PAI-1/body clock relationship among patients who are particularly vulnerable to heart attacks and strokes, such as those with obesity, diabetes, or cardiovascular disease.
- Journal article: “Human circadian system causes morning peak in pro-thrombotic plasminogen activator inhibitor-1 (PAI-1) independent of sleep/wake cycle”
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