Parents must intervene to stop their children overusing social media and consuming time online "like junk food", according to a top official.
In an interview, Children's Commissioner for England Anne Longfield slammed the ways social media giants use to draw children into spending more time.
She said parents should be proactive in stopping their children from bingeing on the internet in the summer holidays.
"It's something that every parent will talk about especially during school holidays; that children are in danger of seeing social media like sweeties, and their online time like junk food," the BBC quoted Longfield as saying in the interview.
"None of us as parents would want our children to eat junk food all the time.
"For those same reasons, we shouldn't want our children to do the same with their online time."
Last year, industry watchdog Ofcom said the internet overtook television as the most popular media pastime for children in the UK.
Children aged five to 15 are spending 15 hours a week on the internet, reports the BBC.
A study earlier this year of screen time and mental well-being among teenagers suggested that moderate use of devices may be beneficial.
The research, which appeared in the journal Psychological Science, was based self-reported data from 120,000 15-year-olds in England.