Hours of TV Viewing a Day Can Make You Seriously Ill, US Study Finds

Ana de Barros, PhD avatar

by Ana de Barros, PhD |

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Television and leisure activities

Findings from a recent study published in the American Journal of Preventive Medicine revealed an association between increasing hours of television viewing per day and risk of death from its major causes in the United States, including Parkinson’s disease.

TV viewing is the most prevalent of leisure-time behaviors in the U.S. with an estimated 289 million Americans (92%) owning a TV. Some 80% of American adults watch TV for an average of 3.5 hours per day, which is more than half (55%) of their available leisure time. In the past 10 years, a growing body of evidence has linked prolonged TV viewing to elevated risk of death from cancer and cardiovascular disease.

In this new study entitled “Causes of Death Associated With Prolonged TV Viewing NIH-AARP Diet and Health Study,”a team of investigators from the National Cancer Institute conducted a prospective research in a cohort or more than 221,426 individuals age 50 to 71 years who, upon study entry, were free of chronic disease. Participants self-reported TV viewing at baseline and most were followed until Dec. 31, 2011 (some died before the study was completed).

After an average follow-up of 14.1 years, the researchers determined an association between TV viewing and higher mortality risk from cancer and heart disease. The results also showed an association between TV viewing and higher risk of death due to  other leading causes, including liver disease, diabetes, influenza/pneumonia, suicide, and Parkinson’s 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,” said lead investigator Sarah K. Keadle, PhD, MPH, Cancer Prevention Fellow, Nutritional Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, in a press release. “Our study has generated new clues about the role of sedentary behavior and health and we hope that it will spur additional research.”

Results showed that in comparison with individuals who watched less than one hour of daily TV those who watched 3 to 4 hours per day were 15% more likely to die from any cause. The results also revealed that those who watched 7 or more hours of TV per day were 47% more likely to die over the research time period. A number of other factors were taken into consideration during the study like smoking, alcohol, caloric intake, and population health status, which could help explain the observed associations. However, these associations remained significant even after researchers controlled for all variables.

Importantly, the harmful effects of TV watching extended to both inactive and active subjects. “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 Dr. Keadle.

More studies are necessary to examine the associations between mortality and TV watching and whether these same associations are found when considering sitting in other contexts, from working to driving or other sedentary leisure-time activities, the researchers said.

“Older adults watch the most TV of any demographic group in the U.S.,” concluded Dr. Keadle. “Given the increasing age of the population, the high prevalence of TV viewing in leisure time, and the broad range of mortality outcomes for which risk appears to be increased, prolonged TV viewing may be a more important target for public health intervention than previously recognized.”

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