Sixteen and 17-year-olds will face an overnight social media curfew and the disabling of addictive features under government plans - but critics say it won't achieve anything as the settings can be turned off.
The initiative is part of Labour's push to protect young people from the harmful effects of the online world.
A ban on social media use for under-16s in the UK was also unveiled last month and is set to take effect in the spring.
Growing concerns over children's mental health and safety online mean more than 40 countries have brought in bans or are considering it.
Technology Secretary Liz Kendall said she also wants to ensure young people aren't suddenly exposed to the most addictive elements of social media when they start using it at 16.
"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," she said.
Under the plans, default settings would stop 16 and 17-year-olds accessing social media between midnight and 6am.
Infinite scrolling - where the app shows an endless stream of content - would also be automatically disabled, as would algorithmic feeds that target users with content based on past behaviour.
Breaks would also be built in to AI chatbot apps.
However, teenagers would be able to turn off these default settings to get the unrestricted experience served to adults.
Conservative shadow education secretary Laura Trott called the plans a "dog's dinner".
"Either they [Labour] 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.
"Giving 16-year-olds the vote while putting them under a social media curfew makes no sense."
Ms Kendall said a consultation with parents and teenagers had shown "even as young people gain greater independence at 16, they should still be protected from the most addictive online features".
A pilot involving more than 300 people also found the curfew helped sleep and concentration, according to the government's Department for Science, Innovation and Technology (DSIT).
New guidance on safe AI use will be published as part of the initiative, while media literacy teaching will be strengthened in schools from September.
The UK's upcoming social media ban for under-16s came after accusations big tech companies are not doing enough to protect children.
The government has called it a "landmark" moment, but there are concerns children will simply find a way around the restrictions and could be pushed on to more dangerous platforms.
The ban will be based around the model used in Australia and is expected to cover the likes of Snapchat, TikTok, YouTube and Instagram - but not messaging services like WhatsApp.
(c) Sky News 2026: UK teenagers to face social media curfew and no infinite scrolling - but can switch it off
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