MONDAY, Oct. 2, 2006 (HealthDay News) -- Too much time spent in front of the television can drag down kids' grades and help spur poor eating habits that lead to obesity.
So conclude two U.S. studies tracking the potentially harmful effects of TV -- and the power of parents to curb those effects.
One study found that more time in front of the TV during weekdays meant poorer school performance at school. Academic achievement was especially impacted for children with unrestricted access to all types of TV programming, the researchers found.
"We found a relationship between watching TV for longer hours on school days and worse school performance," said study author Dr. Iman Sharif, an associate professor of clinical pediatrics at the Children's Hospital of Montefiore and the Albert Einstein College of Medicine in New York City. "There was an even stronger relationship between kids who could watch R-rated movies or whatever they wanted on TV. They did worse in school."
The second study tracked the volume, and types, of food-related advertising included in programming aimed at preschoolers. Most ads were aimed at pulling tots toward long-lasting relationships with particular products, the researchers found.
"The majority of child-oriented food advertisements viewed seemed to take a 'branding' approach -- focusing on creating lifelong customers rather than generating immediate sales," wrote study author Susan Connor, from Rainbow Babies and Children's Hospital in Cleveland. "Promotional spots on advertisement-supported and sponsor-supported networks took similar approaches and used similar appeals, seeming to promote the equation that food equals fun and happiness," she said.
Both studies are published in the October issue of Pediatrics.
According the American Academy of Pediatrics (AAP), the average American child spends about four hours each day in front of the TV. That's far more than the AAP recommendation of no more than one to two hours a day of "screen" time, which also includes time spent playing video games or chatting with friends online.
Previous studies have linked television exposure to increased odds for obesity, aggression and high-risk behaviors, Sharif's study noted. But, most of the previous studies on TV viewing and its effects on children have been conducted on younger children.
Sharif and her colleagues wanted to assess TV and video games' effects on middle school-aged children.
To do so, they tracked the viewing habits of over 4,500 children in grades five through eight, asking the youngsters about their TV viewing and video game-playing habits during the week and on the weekend. They also kept track of each child's school performance by asking kids to rate themselves as excellent, good, average or below average students.
TV watching on weekends did not appear to affect school performance, the researchers found.
However, that wasn't the case for weekday viewing. Of the children that did not watch any TV on weekdays, 50 percent said their school performance was excellent, compared to 42 percent for those who watched less than an hour a day. When TV viewing jumped to between one and three hours daily, the number of kids who said their school performance was excellent dropped to 35 percent.
Programming content mattered, too. Of the group of children whose media content was restricted -- meaning no R-rated movies, and parental guidance for other programming -- 54 percent described their school work as excellent. In contrast, just 22 percent of kids who could watch anything they wanted on TV felt the same way.
"Taking time away from homework results in poorer school performance," theorized Dr. Brenda Kohn, an associate professor of pediatrics at the New York University School of Medicine in New York City. And, she added, "Not only does TV take time away from homework, it takes away from learning sports and learning how to be active to help maintain good health. It sets children up for a sedentary adult life."
In the second study, Connor randomly selected four-hour blocks of children's television from three different stations: PBS, Disney and Nickelodeon. She looked at all of the content aired between the programs.
Out of 48 hours of television, she listed 130 food-related advertisements. That's about 1.3 food-related ads for every half hour of television. More than half were aimed directly at children, according to the study.
Fifty ads were for fast food and 18 were for sugar-sweetened cereals, Connor found. Most of the ads associated food with fun, being happy, having energy or being excited. According to Connor the fast-food ads, in particular, seemed to focus more on brand recognition and positive associations with their products.
"This is not so different than what went on with cigarette smoking, only here they're advertising food of poor nutritional quality, and it's presented in a way that seems palatable," noted Kohn.
"The finding that there are so many food-related ads on all different types of stations is important to understand. It seems like they're less related to product and more to grabbing customers -- no matter if they're 4 or 14," said Dr. Rebecca Unger, an attending pediatrician at Children's Memorial Hospital in Chicago.
She added, "Young children can't tell the difference between advertisements and the programs they're watching."
The bottom line, according to Sharif: "Know how much TV your kids are watching, and know what they're watching."
She added that children shouldn't watch more than two hours of TV daily, and it's even better if you can keep it under one hour, because that's where she said the real differences in schoolwork started to show up.
Also, she said, parents should use the parental block controls provided on TVs or through cable providers to prevent kids from accessing adult content.
Here's some advice on kids and TV from the American Academy of Pediatrics.