Sometimes it seems as though everything that's enjoyable in life is bad for your health, and television is no exception.A number of studies have found links between watching television and premature death, and the more you watch, the more it reduces your lifespan.It's been estimated that once you're over 25, every hour of television you watch reduces your life expectancy by close to 22 minutes.

But it isn't terrible scripts, bad acting or excruciating reality TV programs that are shaving years off our lives; it's what we do, or rather don't do, when we're zoning out in front of the box.For most us, watching television means sprawling on the couch for extended periods. And extended inactivity is known to increase your risk of heart disease, type 2 diabetes, some types of cancers and premature death.

But a recent study from Spain suggests that there might be something else happening when we watch TV. The researchers found people who watched more than three hours of television a day had double the risk of premature death when compared to those who watched less than one hour per day. But when they looked at other sedentary behaviours – driving a car and using a computer – they didn't find the same links with early death. They say more research is needed to help figure out whether there are links between computer use or driving and death rate.

Too much TV can negatively affect brain development, AAP doctors fear, especially in babies, whose brains are growing rapidly.

As reported in the journal Pediatrics in April 2004, researchers at Children's Hospital in Seattle found that the more television a child watches between the ages of 1 and 3, the greater his or her likelihood of developing attention problems by age 7. More specifically, for each extra hour per day of TV time, the risk of concentration difficulties increases by 10 percent, compared with that of a child who views no TV at all. Excessive viewing was associated with a 28 percent increase in attention problems.

The Brain Drain Still, their work is a wake-up call. According to Dr. Christakis, the rapidly moving images on TV and in video games may rewire the brains of very young children, making it difficult for them to focus on slower tasks that require more thought. Others say that TV may, at least temporarily, idle the centers in the pre-frontal cortex that are responsible for organizing, planning, and sequencing thought.