Researchers warn that watching television for three hours a day can double the risk of early death.

According to a new study from Spain, adults who spend time in front of the TV at least three hours a day may be twice as likely to die early than people who watch only an hour or even less.

The team studied 13,284 healthy adults who watched TV for over three hours a day and followed them for about eight years. Among the participants, there were 46 deaths from cancer, 19 deaths due to cardiovascular causes and 32 due to other causes.

"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," Dr. Miguel Martinez-Gonzalez from University of Navarra in Spain said.

After considering other factors related to the twofold higher risk of premature death, the researchers did not see a connection between the increased risk and the time people spent in other inactive activities, including driving or using a computer. However, the risks linked with watching TV appears to be striking. A person's risk of death caused by heart disease increased by 44 percent while the death risk from cancer jumped by 21 percent. The risk of early death from other causes climbed by 55 percent, all compared with people who reported watching less than one hour of TV a day.

The researchers were skeptical about the findings. They said other factors are unclear like whether people were already ill so they watch more television because of their inability to do any other activity. The team ran the figures for a second time minus the 53 deaths which occurred in the first three years of the study period to see who might have already been sick, but the results even got stronger.

People tend to consume more sugary drinks and processed foods while watching TV, so the researchers made adjustments to the numbers to control for the effects of junk foods. Even then, it made the results stronger.

The research was published in the Journal of the American Heart Association.

This new study supports a more recent study that showed the average American increases his risk of cancers for every two hours spent on the computer or TV. It raises the risk of endometrial cancer by 10 percent, colon cancer by 8 percent, and lung cancer by 6 percent. Previous studies also found that people who spend six hours watching TV each day shorten their lifespan by at least five years compared with someone who does not watch TV at all.