Older teenagers in the UK will face an overnight social media curfew, the government has announced – though they will be able to opt out of it by changing their account settings.

It would means apps such as Instagram, TikTok and YouTube being set to be unavailable by default to 16 and 17-year-olds between midnight and 06:00.

The government also wants “addictive” features such as auto-play and infinite scroll to be set to be disabled, saying – combined with the curfew – the measures will improve teenagers’ focus, sleep quality and family life.

However, critics have described the proposals as “piecemeal” and a “missed opportunity” for children’s safety.

The plans follow the announcement in June that under-16s in the UK would be banned entirely from a range of platforms.

“These measures will be crucial in helping young people get the sleep they need, focus on school and college, and spend more quality time with family and friends, all of which are fundamental to building a happy, healthy and fulfilling adult life,” said Technology Secretary Liz Kendall.

“We want young people to enjoy the benefits of technology while having the tools to make the online world a place where they can thrive.”

Laura Trott, the Conservative shadow education secretary, described the plans as a “dog’s dinner”.

“Either they think 16 and 17-year-olds should be on social media or they don’t, but curfews they can simply switch off won’t achieve anything,” she said.

The government said further measures would be aimed at helping children use AI chatbots safely – including by making providers introduce regular breaks for under-18s.

It says it will aim to lay its new proposed measures in front of parliament by the end of 2026, with the aim that they take effect alongside its social media ban for under-16s next spring.

But some child safety charities and experts have cast doubt on the effectiveness or promise of a midnight curfew for older UK teens.

“While we welcome these measures for older teens, this latest move is yet another piecemeal set of announcements not the comprehensive plan for children’s safety that’s required,” said Andy Burrows, chief executive of the Molly Rose Foundation.

He added that Prime Minister Sir Keir Starmer “leaves office having announced a social media ban without a plan” – with his likely successor Andy Burnham to “inherit a series of missed opportunities”.

Meanwhile Prof Sonia Livingstone, an expert in children’s digital rights at the London School of Economics, said a curfew could harm vulnerable children by limiting their access to social media when they might need it most.

“If it’s a curfew on companies using push notifications to wake someone up in the night, absolutely have a curfew,” Prof Livingstone told the BBC.

“But if it’s a curfew that prevents a child in need of support or help or comfort reaching out to trusted sources in the middle of the night, I think that’s quite harmful potentially.”