If you're reading this sitting down, you might consider standing up.

In a provocative look at the impact of sedentary behavior on health, a new study links time watching television to an increased risk of death. One of the most surprising findings is that it isn't just couch potatoes who were affected—even for people who exercised regularly, the risk of death went up the longer they were in front of the TV. The problem was the prolonged periods of time spent sitting still.

Australian researchers who tracked 8,800 people for an average of six years found that those who said they watched TV for more than four hours a day were 46% more likely to die of any cause and 80% more likely to die of cardiovascular disease than people who reported spending less than two hours a day in front of the tube.

Time spent in front of televisions and computers and playing videogames has come under fire in studies in recent years for contributing to an epidemic of obesity in the U.S. and around the world. But typically the resulting public-health message urges children and adults to put down the Xbox controller and remote and get on a treadmill or a soccer field.

The Australian study offers a different take. "It's not the sweaty type of exercise we're losing," says David Dunstan, a researcher at Baker IDI Heart and Diabetes Institute, Melbourne, who led the study. "It's the incidental moving around, walking around, standing up and utilizing muscles that [doesn't happen] when we're plunked on a couch in front of a television." Indeed, participants in the study reported getting between 30 and 45 minutes of exercise a day, on average.