Minority children spend an average of 13 hours a day using mobile devices, computers, TVs and other media — about 4½ hours more than white kids, says a report out today.

The findings, from Northwestern University, are being presented to childhood and telecommunications experts in Washington, D.C.

The results are from an analysis of two Kaiser Family Foundation surveys that tracked media use by kids 6 to 18. Researchers analyzed that data to find out how black, Hispanic, Asian American and white youth use media for homework and for fun, and how long they're plugged in on any given day.

Among 8- to 18-year-olds, Asian Americans logged the most media use (13 hours, 13 minutes a day), followed by Hispanics (13 hours), blacks (12 hours, 59 minutes), and whites (8 hours, 36 minutes.)

Researchers didn't say why, but some experts have theories.

"Children may turn to media if they feel their neighborhoods lack safe places to play or if their parents have especially demanding jobs that prevent engagement," says Frederick Zimmerman, chair of the department of Health Services at UCLA School of Public Health.

"It's clear that, overall, American youth spend an enormous amount of time with media, but minorities spend most of their waking hours with media," says study director Ellen Wartella, head of the Center on Media and Human Development in the School of Communication at Northwestern.

The report shows that compared with white children, minority youth:

•Watch TV and videos one to two hours more a day;

•Listen to music about an hour more a day;

•Use computers about 1½ hours more a day;

•Play video games 30 to 40 minutes longer a day.

Black (84%) and Hispanic kids (77%) also are more likely to have TVs in their bedrooms and to eat meals in front of the TV.

"Everyone is using too much media across the board. There are only so many hours in the day. They're going to miss out on a lot of important things, especially face-to-face contact," says Eleanor Mackey, a clinical psychologist with Children's National Medical Center in Washington, D.C. She says kids need more family time, and the fact that so many are eating dinner with the TV on is "alarming."

"Protect family meal times. We know this to be very important for a child's development," Mackey says.

There shouldn't be a rush to blame or exonerate parents, but rather an effort to try to understand the factors that drive such high levels of use, Zimmerman says.

Growing obesity rates among children, especially minority youth, may also correlate to the high screen time, says Michael Rich, professor of pediatrics at Harvard Medical School, and director of the Center on Media and Child Health at Children's Hospital Boston. He says more research is needed to clarify that relationship, however.

Rich, who blogs online at Askthemediatrician.org, says he is also concerned about the content of media being viewed, and that children are losing valuable sleep hours to electronics, which can affect school performance and behavior.

The research also indicated that among all groups, computer playtime far outweighs computer use for homework in the 8- to 18-year-old age range; only about 16 to 20 minutes a day can be chalked up to school-focused activities, the study shows.

In addition, depending on the primary medium involved, as many as 47% of 8- to 18-year-olds in all groups say that "most of the time" they multi-task with another type of media.

"These findings should be a clarion call to minority communities to protect their children's future health and well-being by insisting on a right to more media-free time," Zimmerman says.