Under-5s should not be on screens for more than an hour a day, parents told in new government advice

Children under the age of five should be limited to one hour of screen time a day, while under-twos should not be watching screens alone, new government guidance says.

It advises parents to steer clear of fast-paced videos and use screens together where possible. The guidance also suggests "screen swaps" - taking screens away to read stories together or playing simple games at mealtimes.

The guidance is the first evidence-backed, practical advice issued by the government, but ministers say it will be kept under review as more evidence emerges.

"This is still quite an unknown area in lots of respects and we've taken a precautionary approach," Education Secretary Bridget Phillipson said.

Children's commissioner for England Dame Rachel de Souza and Department for Education scientific adviser Prof Russell Viner have reviewed the latest evidence, finding that long periods of time spent on screens alone can affect children's sleep and physical activity, which are key to their development.

The government has previously said about 98% of children are watching screens on a daily basis by the age of two.

But the new guidance says not all screen time is the same - watching screens with an engaged adult is linked to better cognitive development than solo use.

Ahead of the guidance for under-fives being published on Friday, BBC News followed the Montastier family in Manchester for a week as they tried to cut back on screen time.

Mum Alexis says screen time is a "topic of conversation every day - because we do it every day".

She is keen to cut down on the family's screen time as her children Romi, four, and Marlo, one, grow up surrounded by technology.

The yoga instructor says she normally resorts to screens if she needs to do something quickly, like pack their school bags or cook.

It might also happen when Romi wakes up early, and sometimes it's simply "to avoid conflicts and meltdowns".

"It does make me feel guilty for doing it, but you're not always going to be getting out of bed bouncing with them at six o'clock and setting up art and crafts."

Alexis says following the new rules hasn't been easy.

"At the start of the week I was like, 'Yeah come on, we're going to do this,' and by the end of the week I thought we would have no screens and everything would just swap perfectly - but it didn't really happen like that. We've tried our best."

She says she found some swaps very time-consuming - especially in the morning and right after school when she needed to get things done.

"I need that time, so I'm not going to swap it to sit down and read a book because it's not realistic," she says.

Her husband Marciel says "it's hard to tell them not to when you're doing it yourself".

As someone who is on his screen a lot for work, he says he has the "rush of needing to look at my phone if it's for work during the day, and it keeps going after work".

But the family are going to keep trying.

"This has definitely made me more aware and almost made me start doing things that I've always said, 'Oh, we need to do that,'" Alexis says.

At the Institute for the Science of Early Years at the University of East London, scientists have been studying the different content watched by under-fives.

Observing three-year-old Alex's brain activity using a sensory cap, Prof Sam Wass says he is particularly interested in "moments where his brain can't keep up anymore, where the content is happening at a speed which is too fast for his brain to track".

"If stuff is coming at us too fast, something called the fight or flight stress system kicks in, where your heart starts beating faster and you start to get a lot of energy released to your muscles," he says.

"Of course, this isn't actually useful anymore, because this is happening when children are sat still on a chair watching screen content."

The researchers say the nature of content aimed at children has changed significantly over the past 20 to 30 years.

Previously, children's programmes were generally much more slow-paced, while today's content is much faster, featuring lots of movement and talking.

Wass says not much is yet known about how the change is affecting children, but that there is "good evidence" of a link between emotional dysregulation - an inability to manage emotional responses - and the amount of time spent watching fast-paced, unpredictable content.

"This is something that we need to be looking at carefully," he says.

The guidance says time limits shouldn't apply in the same way for the screen-based assistive technologies used to support children with special educational needs and disabilities.

"I know there are lots of pressures on families and the intention behind the guidance is not to be judgmental, but to be supportive and to provide that clear practical help that parents have been telling us they really want to see," Phillipson said.

The guidance also recommends that artificial intelligence (AI) toys or tools should be avoided.

But Vicki Shotbolt, founder of Parent Zone, which supports families to stay safe online, says it's very hard for young children to completely avoid tech.

She says she hopes parents will not become unnecessarily worried by it.

"A small child under the age of five who's got an AI smart speaker in the house will be interacting with it," she says.

"So the idea that we can completely keep them away from it is probably flawed, but it's good general guidance."

It comes as the government is separately carrying out a consultation on whether the UK should follow in Australia's footsteps by making it illegal for under-16s to have access to many social media sites.