A provocative new study discovers a link between television viewing and poor health in the U.S., where 80 percent of Americans watch 3.5 hours of television per day.
Investigators report an association between increasing hours of television viewing per day and increasing risk of death from most of the major causes of death in the United States.
The study appears in the American Journal of Preventive Medicine.
Virtually all Americans (92 percent) have a television at home. For many Americans, watching TV has literally become the American pasttime consuming more than half of their available leisure time, potentially displacing more physical activities.
Previous studies had reported a relationship between TV viewing and elevated risk of death from cancer and cardiovascular disease. In this study, researchers at the National Cancer Institute looked at more than 221,000 individuals aged 50-71 years old who were free of chronic disease at study entry.
Investigator discovered a higher mortality risk from cancer and heart disease among people who watched television the most. In addition, they identified new associations with higher risk of death from most of the leading causes of death in the U.S., such as, diabetes, influenza/pneumonia, Parkinson’s disease, and liver disease.
“We know that television viewing is the most prevalent leisure-time sedentary behavior and our working hypothesis is that it is an indicator of overall physical inactivity. In this context, our results fit within a growing body of research indicating that too much sitting can have many different adverse health effects,” explained lead investigator Sarah K. Keadle, Ph.D., M.P.H.
Keadle cautioned that although each of the associations observed have plausible biological mechanisms, several associations are being reported for the first time and additional research is needed to replicate these findings and to understand the associations more completely.
“Our study has generated new clues about the role of sedentary behavior and health and we hope that it will spur additional research.”
The study found that compared to those who watched less than one hour per day, individuals who reported watching three to four hours of television watching per day were 15 percent more likely to die from any cause; those who watched seven or more hours were 47 percent more likely to die over the study period.
Researchers found that risk began to accrue at three to four hours per day for most causes they examined. The investigators took a number of other factors into consideration that might explain the associations observed, such as caloric and alcohol intake, smoking, and the health status of the population, but when they controlled for these factors in statistical models, the associations remained.
Another important finding of the study is that the detrimental effects of TV viewing extended to both active and inactive individuals. Still, being active helped to mitigate at least some of the risks.
“Although we found that exercise did not fully eliminate risks associated with prolonged television viewing, certainly for those who want to reduce their sedentary television viewing, exercise should be the first choice to replace that previously inactive time,” said Keadle.
Investigators caution that more research is needed to explore connection between TV viewing and mortality and whether these same associations are found when we consider sitting in other contexts, such as driving, working, or doing other sedentary leisure-time activities.