Physical Fitness Suffers

The more television people watch, the less exercise they get. If you turn the TV off, you might go outside, take the dog for a walk or get your body moving simply by doing some housework. If you leave it on and sit in front of it, muscles can atrophy, the heart rate can drop, as can the level of oxygen in your blood. Too much TV has been linked to the rising rate of obesity.

Attention Suffers

Some researchers think there may be a link between watching a lot of TV and ADD or ADHD in both children and adults. It does seem to train the human mind to think, analyze and focus only in very short spurts. TV watchers have difficulty paying attention to lectures in class or writing papers in which they sustain their arguments for any length, because they simply cannot focus over long periods of time.

Reading Suffers

Kids who sit in front of the television for several hours a day lag behind their peers in reading skills. They just aren't using their time to read; instead they are watching TV, something that takes much less mental work, therefore giving them much less mental exercise. Adults who prefer the passive entertainment of television will often say, "I don't have time to read."

School and Work Performance Suffers

If children stay up late watching TV, they aren't getting enough sleep to do well in school. If adults aren't giving their minds a rest from the relentless flow of sound and image, their brains don't have the space to work on ideas and problems. Also, TV is a passive medium; in most cases, the solution to any problems is given by the end of the program. The viewer doesn't have to think creatively or do independent problem solving. It's all done for him.

Values Suffer

Many of the values portrayed on television are not those embraced by most Americans. But television show portray choices, lifestyles and attitudes as though they were the norm, and viewers often come to believe it. Kids pick up language and attitudes toward their parents and teachers, and adults pick up a sense that everyone must be living like they do on TV. It's not always easy to remember it's make-believe.

Source:

Alabama Cooperative Extension System

Neuropsychiatry Review

CNN

More Information:

CNN.com