How much time does your preteen or teen spend online, watching TV, listening to music or playing video games? Turns out the answer may be linked to their racial and ethnic background.

A new study out of Northwestern University has found dramatic differences in the amount of time kids from different ethnic and racial minorities in the U.S. spend online, compared with their white counterparts. Read the full report here.

“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,” according to the report.

The sheer number of hours is staggering: 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).

The added time was divided between television, music, Internet and video gaming, but the proportion of television consumption in particular was highest for minority youth, who were also more likely to have televisions with cable and specialty channels in their bedrooms.

“In the past decade, the gap between minority and white youth’s daily media use has doubled for blacks and quadrupled for Hispanics,” says Northwestern Professor Ellen Wartella, who directed the study and heads the Center on Media and Human Development in the School of Communication. “The big question is what these disparities mean for our children’s health and education.”

The study, “Children, Media and Race: Media Use Among White, Black, Hispanic and Asian American Children,” is based on a new analysis, by race, of data from the Kaiser Family Foundation’s previous media use studies. It finds that race-related differences among youth are robust even when controlling for factors including parent education and whether or not children are from single- or two-parent families.

Media usage among kids and teens has shifted dramatically in the last 10 years, and these changes have consequences for families, schools and communities. One Kaiser Family Foundation report found that 8-18 year-olds of all racial backgrounds pack in more than 53 hours a week of media usage (more than a full-time job!). And what’s more, since kids are so adept at media multitasking, the average 7 hours, 38 minutes of media time a day actually condenses almost 11 real time hours of media.

Compare this to how much time your kids spend in school. To how much time they spend with you.

The scale of influence is so dramatically different that it pales in comparison. Do you feel your preteens and teens are adequately prepared to process all these outside messages about their bodies, their sexuality, their values, their life choices?

Parents of all kids, no matter their colour, race or ethnicity, need to carefully examine their kids’ media usage. But the need is clearly greatest in minority communities.

“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,” Frederick Zimmerman explained in a USA Today article on the report, chair of the department of Health Services at UCLA School of Public Health.