In comparison, they will have spend only 900 hours sitting in a classroom. This is not good news. Studies show that excessive TV watching is associated with all sorts of bad things, like poor school performance, a diminished attention span, and an increase in aggressive behavior. Too much television watching also makes teens feel less secure and worry more that they will be a victim of crime. Teens who watch a lot of TV also evidence lower social trust and are less engaged with peers.
TV also makes kids fat.
That's because kids who watch TV a lot are less likely to engage in physical exercise. The negative effects of kids watching too much TV is not confined to childhood. For example, 16.7 percent of the young adult women who had watch a lot of television violence as girls, reported having punched, beat or choked another adult, compared to only 3.6 percent of young adult women who had not watched a lot of television violence as kids. For young adult men, the rates were even higher. Thirty-seven percent of the young men who had watched a good deal of television violence as children reported having thrown something at a partner during an argument, compared to only 16 percent of low violence television viewers.