PRESS ASSOCIATION -- Watching TV for an average of six hours a day can cut life expectancy by five years, according to new research.
A sedentary lifestyle - as opposed to just not taking enough exercise - increases the risk of dying, particularly from heart attack and stroke.
Watching TV accounts for a large part of people's sedentary living, but time sitting down and in cars also counts, said researchers writing in the British Journal of Sports Medicine.
They warned that watching TV is a "public health problem" comparable to issues such as smoking and obesity.
Using information from the Australian Diabetes, Obesity and Lifestyle Study, together with population and death rate data, experts from the University of Queensland calculated lifetime risk from TV watching.
The study involved more than 11,000 people over the age of 25 and data was gathered on how much time was spent watching TV or videos/DVDs.
The experts found that, on average, every single hour of TV viewed after the age of 25 reduced the viewer's life expectancy by almost 22 minutes. Around six hours of daily viewing can cut a person's lifespan by almost five years, they added.
"TV viewing time may be associated with a loss of life that is comparable to other major chronic disease risk factors such as physical inactivity and obesity," the team concluded.
This finding is also comparable to risk factors such as smoking, with other research showing that one cigarette cuts 11 minutes off a lifespan - equivalent to half an hour of TV watching.
The experts added: "While we used Australian data, the effects in other industrialised and developing countries are likely to be comparable, given the typically large amounts of time spent watching TV and similarities in disease patterns."