Watching too much TV may increase risk of early death: Three hours a day linked to premature death from any cause

"Television viewing is a major sedentary behavior and there is an increasing trend toward all types of sedentary behaviors," said Miguel Martinez-Gonzalez, M.D., Ph.D., M.P.H., the study's lead author and professor and chair of the Department of Public Health at the University of Navarra in Pamplona, Spain. "Our findings are consistent with a range of previous studies where time spent watching television was linked to mortality."

Researchers assessed 13,284 young and healthy Spanish university graduates (average age 37, 60 percent women) to determine the association between three types of sedentary behaviors and risk of death from all causes: television viewing time, computer time and driving time. The participants were followed for a median 8.2 years. Researchers reported 97 deaths, with 19 deaths from cardiovascular causes, 46 from cancer and 32 from other causes.

The risk of death was twofold higher for participants who reported watching three or more hours of TV a day compared to those watching one or less hours. This twofold higher risk was also apparent after accounting for a wide array of other variables related to a higher risk of death.

Researchers found no significant association between the time spent using a computer or driving and higher risk of premature death from all causes. Researchers said further studies are needed to confirm what effects may exist between computer use and driving on death rates, and to determine the biological mechanisms explaining these associations.

"As the population ages, sedentary behaviors will become more prevalent, especially watching television, and this poses an additional burden on the increased health problems related to aging," Martinez-Gonzalez said. "Our findings suggest adults may consider increasing their physical activity, avoid long sedentary periods, and reduce television watching to no longer than one to two hours each day."

The study cited previous research that suggests that half of U.S. adults are leading sedentary lives.

The American Heart Association recommends at least 150 minutes of moderate-intensity aerobic activity, or at least 75 minutes of vigorous aerobic activity each week. You should also do moderate- to high-intensity muscle strengthening at least two days a week.