Considering TV-watching an activity could be dangerous to your residents’ health. A new study published in the December issue of the American Journal of Preventive Medicine found 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.

For this study, researchers at the National Cancer Institute looked at more than 221,000 individuals aged 50 to 71 years who were free of chronic disease when they entered the study. The researchers identified an association between TV-watching and a higher risk of death from most of the leading causes of death in the United States, such as cancer, heart disease, 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,” said lead investigator Sarah K. Keadle, Ph.D., M.P.H., Cancer Prevention Fellow, Nutritional Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute. Older adults watch the most TV of any demographic group in the United States, she added. Keadle cautioned that additional research is needed to replicate these findings and to understand the associations more completely.

The study found that, compared with those who watched less than one hour per day, individuals who reported watching three to four hours of television were 15% more likely to die from any cause. Those who watched seven or more hours were 47% more likely to die over the study period. The investigators considered that other factors 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.

The detrimental effects of TV-viewing extended to both active and inactive individuals. “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,” Keadle said.

Investigators caution that more research is needed to explore the connection between TV-viewing and mortality and whether these same associations are found when sitting in other contexts, such as driving, working or doing other sedentary leisure-time activities.