MONDAY, Jan. 10 (HealthDay News) -- Too much time spent watching TV or sitting in front of a computer may increase your risk for heart disease and even shorten your life, a new British study found.

In fact, if you spend four hours a day or more of your leisure time watching TV, using the computer or playing video games, you are more than two times more likely to suffer a heart attack, stroke, heart failure or die, according to the study.

"Our research suggests that screen time and perhaps sitting in general can be very detrimental for overall and cardiovascular health," said lead researcher Emmanuel Stamatakis, a senior research associate in the department of epidemiology and public health at University College London.

"Given that the large majority of people of working age have sedentary jobs and spend long periods of time commuting or driving, which involve even more sitting, leisure time should involve as little sitting and as much movement as possible," he said.

The report is published in the Jan. 18 issue of the Journal of the American College of Cardiology.

For the study, Stamatakis's team collected data on 4,512 adults who responded to the 2003 Scottish Health Survey, which among other things asked about leisure time activities.

During 4.3 years of follow-up, 325 of these people died and 215 had a cardiovascular event, the researchers reported.

Stamatakis' group found that compared with those who spent less than two hours a day in front of a screen, those who spent four or more hours watching TV or playing or working on the computer had a 48 percent increased risk for dying from any cause and a 125 percent increased risk for having a heart attack, stroke or heart failure.

Moreover, the risk calculations remained even after taking into account such factors as smoking, high blood pressure, weight, social class and exercise, the researchers noted.

"Importantly, participation in exercise did not seem to mitigate against the harms associated with excessive screen times," Stamatakis said.

In addition, biology appears to play a role. For example, one-fourth of the link between screen time and heart attack was associated with levels of C-reactive protein, which is a marker of inflammation along with weight and cholesterol, suggesting that inflammation and high cholesterol, combined with sitting, may increase the risk for cardiovascular events, the researchers said.

One way to keep healthy is to limit the amount of time spent sitting, Stamatakis said. Start by watching less TV, which many people do three to four hours a day, he added.

"This is excessive," he said. "And besides, TV watching [is] a waste of time in the most passive and uncreative way, in most cases. It also displaces hugely beneficial physical activity and, according to our findings, is also linked to unique and distinct risks for health."

Commenting on the study, Dr. Suzanne Steinbaum, a preventive cardiologist at Lenox Hill Hospital in New York City and a spokeswoman for the American Heart Association, said that "what I like about this study is it helps us understand the significant role that a sedentary lifestyle has on the risk of heart disease."

"We are all so fixated during the workday on the computer, and sitting has become such a regular part of our lives, that if we choose to sit for leisure, it's really harmful for us," she said.

Steinbaum recommends doing something physical every day -- and not sitting when you don't have to. "Leisure activity should be something that helps get [you] moving, no matter what this is," she said.

More information

The American Heart Association has more on preventing heart disease.