Maybe our TVs, like our cigarette packages, need health-warning labels.
On the heels of a Harvard study that linked TV watching with an increased risk of diabetes, heart disease and premature death comes a new Australian study that quantifies the premature-death risk in even blunter terms:
Each hour we adults spend in front of a television shortens our life expectancy by an average of about 22 minutes, the study found.
Since the average American adult spends 35.5 hours a week watching TV, that means we’re shaving almost 13 hours from our lives each week.
OK. OK. The study did not find that TV viewing actually caused a decrease in life expectancy. It found only an association between the two. Still, these findings add to a growing body of research that suggests being sedentary (sitting too much) is a major risk factor for a shortened life span.
In fact, the current study found that TV viewing may be as detrimental to your life expectancy as some well-known risk factors, such as smoking and not exercising.
The study’s details
For this study, which appeared online Tuesday in the British Journal of Sports Medicine, researchers from the University of Queensland used published data from the large (11,000 participants) and ongoing Australian Diabetes, Obesity and Lifestyle Study (AusDiab). That data had previously revealed an association between TV viewing (participants had been surveyed about their TV habits) and an increased risk of premature death from all causes — even after adjusting for such things as smoking, exercise habits, diet, high blood pressure and cholesterol levels.
According to the data, Australian adults aged 25 and older watched 9.8 billion hours of television in 2008. Using Australian mortality figures from that same year, the authors of Tuesday’s study estimated the extent to which TV viewing reduced life expectancy.
They calculated that individuals who spend a lifetime average of six hours per day watching TV can expect to live 4.8 years less than those who watch no TV.
To put it another way: Every single hour of TV viewed after the age of 25 reduces the viewer’s life expectancy by 21.8 minutes.
If no one watched TV, according to the mathematical modeling used in the study, the 2008 life expectancy at birth would have been 1.8 years longer for Australian men and 1.5 years longer for Australian women.
It’s unlikely these findings are unique to Aussies. “While we used Australian data,” write the study’s authors, “the effects in other industrialized and developing countries are likely to be comparable, given the typically large amounts of time spent watching TV and similarities in disease patterns.”
Comparing the risk
The negative impact on health associated with TV viewing in this study is similar to that of other well-known lifestyle factors. As the authors of this study point out, other risk models have estimated that each cigarette smoked reduces an individual’s life expectancy an average of 11 minutes, and that lifelong smoking is associated with a loss of life after age 50 of 4.3 years for men and 4.1 years for women — the equivalent of 6.0 and 6.4 daily hours of TV watching.
Other research has shown that low physical activity after age 50 reduces life expectancy by about 1.4 years compared with moderate physical activity and about 3.6 years compared with high physical activity — the equivalent of watching 2.1 and 5.4 hours, respectively, of TV a day.
“TV viewing time may have adverse health consequences that rival those of lack of physical activity, obesity and smoking,” conclude the study’s authors. “… A public health case could be made that adults [as well as children] need to limit the time spent watching TV.”