Teenagers with a bedroom television tend to have poorer diet and exercise habits and lower grades in school than those without one, US researchers said on yesterday.

While many studies have examined TV viewing habits of young people, researchers at the University of Minnesota School of Public Health said little had been known about the consequences in particular for older adolescents of having a bedroom TV.

They questioned 781 adolescents, ages 15 to 18, in the Minneapolis area in 2003 and 2004. Of them, 62 percent reported having a television in their bedroom.

Not surprisingly, those with a bedroom TV were more apt to watch it a lot, clocking four to five more hours in front of a television per week, the researchers said. Twice as many of the teens with a bedroom TV were classified as heavy TV watchers - at least five hours a day - compared to those without one.

Girls with a bedroom television reported getting less vigorous exercise - 1.8 hours per week compared to 2.5 hours for girls without a TV. They also ate fewer vegetables, drank more sweetened beverages and ate meals with their family less often, the researchers said.

Boys with a bedroom TV reported having a lower grade point average than boys without one, as well as eating less fruit and having fewer family meals, the researchers said.

The American Academy of Pediatrics urges parents to remove TV sets from children's bedrooms.

Boys were more likely to have a television in their bedroom than girls - 68 percent versus 58 percent.

Teens from the highest income families were far less likely than those from all other income levels to have a bedroom TV, the survey found.

Among black teens, 82 percent reported having a bedroom TV, compared to 66 percent of Hispanics, 60 percent of whites and 39 percent of Asian Americans.

The researchers tracked body mass index - a measure based on height and weight - and found that having a bedroom TV had no influence on whether teens were obese.

Researchers said that finding was a surprise, considering that previous studies looking at younger children - one on elementary school kids and one on low-income preschoolers - found that having a bedroom TV was an even stronger predictor of obesity than the time spent watching TV.