More evidence on TV's deadly impact
Bad reception Each hour of TV you watch could cut 22 minutes from your lifespan, a new Australian study has found.
"If our estimates are correct, then TV viewing is in the same league as smoking and obesity," says Veerman.
An Australian study by Professor David Dunstan of the Baker IDI Heart and Diabetes Institute in Melbourne, and colleagues, last year found an hour of TV viewing a day led to an 8 per cent higher risk of premature death, especially from cardiovascular disease.
"We've taken that study and translated it into what it means for life expectancy in Australia given how much TV we view," says Veerman.
His team estimates that every single hour of TV watched after age 25 is associated with a reduction in life expectancy of around 22 minutes.
"Given that Australians watch on average around two hours of TV a day, that would reduce life expectancy at birth by 1.8 years for men and about 1.5 years for women," he says.
Veerman says the small proportion of people who watch six hours of television a day would reduce their lifespan by 4.8 years.
Comparable to smoking
Veerman says according to conservative estimates every cigarette costs us 11 minutes of life and the average smoker lives 10 years less than someone who has never smoked.
"At the individual level there are few things worse you can do than smoking," says Veerman.
But, he says, when you consider that fewer and fewer people smoke but almost everybody watches TV, at a population level, TV viewing is also a serious threat to public health.
Veerman says that while the figures from his study are statistically significant there is a large degree of uncertainty surrounding them, probably because the 11,000 people involved in the study still constitutes a small sample.
But, he says other studies, for example from England and Scotland, have also found TV viewing reduces lifespan.
Veerman says a recent analysis of all such studies in the Journal of the American Medical Association suggests the risk from TV viewing is lower than their findings.
"If you apply these pooled results, then for every single hour of TV that you watch after age 25 you could on average expect to lose five minutes of your lifetime."
He says the differences in estimates may be attributable to different age groups being studied, and a different interpretation of TV viewing.
His study only classified someone as watching TV if they were doing nothing else at the time, such as cooking or some other activity.
Veerman says there will need to be follow-up studies involving more people, possibly wearing accelerometers that measure how much people are moving.
In related news, a study in The Lancet released today finds that just 15 minutes of physical activity per day reduces a person's risk of death by 14 per cent and increases life expectancy by three years, compared to inactive people.
This could be good news for those who try unsuccessfully to follow guidelines that recommend a minimum of 30 minutes a day exercise.
Veerman is surprised by the estimates of increased life expectancy found in the study, but he says it suggests any amount of physical exercise is good.
"The more exercise you do the better but every step counts," says Veerman.
Unfortunately though, this doesn't mean you can offset the risk from excessive TV watching by running around the block.
"There is still an independent risk of extended periods of sitting," says Veerman.
Last year Dunstan and team found even people who exercised were still at increased risk of premature death if they also watched high amounts of television.