Here’s one simple way to keep your children healthy: Ban the TV in their bedroom.
My Take?
A friend sent along a copy of a New York Times Opinion Piece by Tara Parker-Pope that was published on March 4, 2008. 
Ms. Parker-Pope sounds like she read my book, God’s Design for the Highly Healthy Child.  Nevertheless, I thought you’d enjoy seeing her excellent review on the topic:
“By some estimates, half of American children have a television in their bedroom; one study of third graders put the number at 70 percent. And a growing body of research shows strong associations between TV in the bedroom and numerous health and educational problems.
“Children with bedroom TVs score lower on school tests and are more likely to have sleep problems. Having a television in the bedroom is strongly associated with being overweight and a higher risk for smoking.
“One of the most obvious consequences is that the child will simply end up watching far more television — and many parents won’t even know.
“In a study of 80 children in Buffalo, ages 4 to 7, the presence of a television in the bedroom increased average viewing time by nearly nine hours a week, to 30 hours from 21. And parents of those children were more likely to underestimate their child’s viewing time.
““If it’s in the bedroom, the parents don’t even really know what the kids are watching,” said Leonard H. Epstein, professor of pediatrics and social and preventive medicine at the School of Medicine and Biomedical Science at the State University of New York at Buffalo. 
“Oftentimes, parents who have a TV in the kids’ bedrooms have TVs in their bedrooms.”
Moreover, once the set is in the child’s room, it is very likely to stay. “In our experience, it is often hard for parents to remove a television set from a child’s bedroom,” Dr. Epstein said.
Dr. Epstein and his colleagues put monitoring devices on bedroom TVs and all the other sets in the house. In one two-year study, the devices in half the homes were programmed to reduce children’s overall viewing time by half. (Children had to use a code to turn on any TV in the home, and the code stopped working once the allocated TV time for the week had been reached.)
Although all the children in the study gained weight as they grew, relative body mass index dropped among those with mandatory time limits. The researchers found that cutting into TV time did not increase exercise levels. Instead, the children snacked less, lowering their consumption more than 100 calories a day. 
The study, published in The Archives of Pediatrics and Adolescent Medicine, did not break down the data by bedroom television viewing.
But in 2002, the journal Pediatrics reported that preschool children with bedroom TVs were more likely to be overweight. 
A study in the journal Obesity suggested that the risk might be highest for boys. 
In a study among French adolescents, boys with a bedroom television were more likely than their peers to have a larger waist size and higher body fat and body mass index.
The French study also showed, not surprisingly, that boys and girls with bedroom TVs spent less time reading than others.
Other data suggest that bedroom television affects a child’s schoolwork. 
In a 2005 study in The Archives of Pediatric and Adolescent Medicine, researchers looked at the television, computer and video game habits of almost 400 children in six Northern California schools for a year. 
About 70 percent of the children in the study had their own TV in the bedroom; they scored significantly and consistently lower on math, reading and language-arts tests. Students who said they had computers in their homes scored higher.
Why a bedroom television appears to have such a pronounced impact is unclear. It may be that it’s a distraction during homework time or that it interferes with sleep, resulting in poorer performance at school. It could also suggest less overall parental involvement.
Another study, published in Pediatrics, showed that kindergartners with bedroom TVs had more sleep problems. Those kids were also less “emotionally reactive,” meaning that they weren’t as moody or as bothered by changes in routine. 
While that sounds like a good thing, the researchers speculated that having a TV in the bedroom dampened the intensity with which a child responded to stimulation.
Another study of more than 700 middle-school students, ages 12 to 14, found that those with bedroom TVs were twice as likely to start smoking — even after controlling for such risk factors as having a parent or friend who smokes or low parental engagement. 
Among kids who had a TV in the bedroom 42 percent smoked; among the others, the figure was 16 percent.
“I think it matters quite a lot,” Dr. Epstein said. “There are all kinds of problems that occur when kids have TVs in their bedroom.”
So while many parents try to limit how much television and what type of shows their children watch, that may be less than half the battle. 
Where a child watches is important too.