Television viewing has often been accused of rotting the human brain, but it seems the real risk may be that it is doing some damage to the rest of your body.

Australian scientists have published research showing a link which suggests that the more TV a person watches, the sooner they die.

The report, which appears in the journal Circulation,says every extra hour spent watching television increases people's risk of premature death.

Professor David Dunstan of the Baker IDI Heart and Diabetes Institute in Melbourne, followed more than 8000 Australian adults for six years.

The team discovered that the people who watched the most TV died younger.

"What this study provides is the first compelling evidence linking television viewing to an increased risk of early death," says Dunstan.

"People who watch four or more hours of television a day have a 46% higher risk of death from all causes and 80% increased risk of death from cardiovascular disease."

Dunstan says the increased risk of premature death was independent of other risk factors like smoking, blood pressure, cholesterol, diet or exercise.

He says that shows too much sitting is bad for our health.

"[Watching TV involves] prolonged sitting, because that's the default position, and from that there's an absence of muscle movement," he says.

"We know from extensive evidence that muscle contractions are so important for many of the body's regulatory processes, such as breaking down and using glucose, so that loss of muscle movement for prolonged periods may result in a disruption to the body's regulatory processes."

Sitting down

The report stresses that sitting too much is different from not exercising enough.

"The risk associated with prolonged sitting are also not necessarily offset by doing more exercise," says Dunstan.

"Because in this study even people who were exercising, if they also watched high amounts of television, they had an increased risk of premature death."

Dunstan says the team also has preliminary evidence indicating that nearly three-quarters of the working hours of office-based employees are spent sitting down.

Trevor Shilton from the Heart Foundation says the research highlights a vitally important new field of study.

"In just a couple of generations we've gone from being a very active people to people who sit around for most of the day," he says

"I can foresee a time where we will have, in addition to our guidelines, a defined 30 minutes of physical activity, also guidelines about moving more and standing more throughout the day.

"And about sitting less, standing up every 20 minutes, going for a walk at work, having rules around television and computer times for our kids."

ABC Science