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Too much screen time boosts heart disease, death risk

Kathleen Blanchard's picture

Too much couch time, or sitting for prolonged periods, can be dangerous say researchers.

Sitting in general is bad for heart health and can lead to death from all causes. Scientists found those who sit more than four hours a day have a significantly higher chance of dying from heart disease or any cause, compared to people who spend less than 2 hours a day engaged in front of a computer or TV screen.

The reason sitting for prolonged periods of time is dangerous to health may be from inflammation brought about by metabolic factors. The authors found C-reactive protein, a biomarker for inflammation, increases in response to inactivity; that was found to be four times lower in people who sit less than 2 hours. Other reasons for the health risks of being a couch potato include dysregulation of lipids, and also linked to increased body mass index.

"People who spend excessive amounts of time in front of a screen - primarily watching TV - are more likely to die of any cause and suffer heart-related problems," said Emmanuel Stamatakis, PhD, MSc, Department of Epidemiology and Public Health, University College London, United Kingdom. "Our analysis suggests that two or more hours of screen time each day may place someone at greater risk for a cardiac event."

The authors found the chances of heart disease increase 125 percent for people who spend two or more hours a day engaged in screen-based entertainment, and 48 percent higher risk of death from any cause, compared to those who spend less than two hours a day sitting at a computer or in front of a television.

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Dr. Stamatakis says for many it's a matter of habit. Watching TV after work for several hours is "convenient", but bad for health, especially because exercising may not reverse the health risks of sitting for so long. He says the finding "underscores the urgent need for public health recommendations to include guidelines for limiting recreational sitting and other sedentary behaviors, in addition to improving physical activity."

The findings come from a study of 4,512 adults participating in the 2003 Scottish Health Survey who self-reported time spent in front of the TV or computer. During the four-year follow up there were a total of 325 all-cause deaths and 215 cardiac events.

Excluded from the analysis were individuals with previous cardiovascular events. The authors were also careful to exclude individuals who might be spending time watching TV or at the computer because of existing illness or physical limitations.

The research findings show sitting for too long may have irreversible consequences that raise the risk of heart disease and increasing the chances of over all mortality. The study authors plan to find out if exercise can lessen the consequences of being a couch potato, what exactly prolonged sitting does to the body and what can be done to change lifestyle habits to reduce sitting time.

J Am Coll Cardiol 2011 57: 292-299.