Parents should limit kids' tweeting and texting and keep smartphones and laptops out of bedrooms, a US paediatricians group says.
The recommendations are bound to prompt eye-rolling and laughs from many teens but the influential paediatricians group American Academy of Pediatrics says parents need to know that unrestricted media use can have serious consequences.
It's been linked with violence, cyberbullying, school woes, obesity, lack of sleep and a host of other problems.
It's not a major cause of these troubles, but "many parents are clueless" about the profound impact media exposure can have on their children, said Dr Victor Strasburger, lead author of the new policy.
"This is the 21st century and they need to get with it," said Strasburger, a University of New Mexico adolescent medicine specialist.
The policy is aimed at all kids, including those who use smartphones, computers and other internet-connected devices.
It expands the academy's longstanding recommendations on banning televisions from children's and teens' bedrooms and limiting entertainment screen time to no more than two hours daily.
Under the new policy, those two hours include using the internet for entertainment, including Facebook, Twitter, TV and movies; online homework is an exception.
The policy statement cites a 2010 report that found US children aged eight to 18 spend an average of more than seven hours daily using some kind of entertainment media.
Many kids now watch TV online and many send text messages from their bedrooms after lights out, including sexually explicit images by mobile phone or internet, yet few parents set rules about media use, the policy says.
"I guarantee you that if you have a 14-year-old boy and he has an internet connection in his bedroom, he is looking at pornography," Strasburger said.
The policy notes that three-quarters of kids aged 12 to 17 own mobile phones; nearly all teens send text messages, and many younger kids have phones giving them online access.
"Young people now spend more time with media than they do in school - it is the leading activity for children and teenagers other than sleeping," the policy says.