Pupils at a school in Kent have given up their smartphones as part of an experiment to monitor their behaviour.
Year 10 students at The Canterbury Academy Trust who handed in their phones said it was a "scary" prospect, but also "a relief".
As part of a research project by the University of Kent, the pupils will not have access to their smartphones for one week.
Experts said they wanted to track the change in the behaviour of students and the impact it has on them.
Emilia and Molly handed in their smartphones on Monday morning.
Molly said: "It's a nice bit of freedom because you don't have to constantly be checking your messages and see you're missing out on things."
Meanwhile, Emilia added: "I think it's going to improve our mental health and mental wellbeing because you're not constantly looking at your phone, you can actually get on with things that you're meant to."
The pupils have been given a basic Nokia phone for the week, with no access to social media.
Jon Watson, chief executive officer of The Canterbury Academy Trust, is also taking part in the trial, which has previously been carried out at two Kent schools.
He said phone use was already restricted during the school day, but the experiment included when staff and pupils returned home.
"I thought it was important that I set that example, so that I can be present and in the moment," he said.
"It's about helping young people understand the power and responsibility they have when they are in possession of a smartphone, how positive they can be in terms of what they can do, but also some of the negatives and some of the challenges they'll face while they have that mobile phone as well."
Participants are to be interviewed at the start and at the end of the week by Dr Lindsey Cameron, a psychology lecturer at the University of Kent.
"We know there's a link between smartphone use and mental health, problems with sleep, comparing yourselves to others - and phones are really addictive.
"We really have to understand what effect this is having on young people."
This week, six primary schools and more than 5,000 parents and caregivers in Kent signed up to a pact that promised to delay smartphone use in teenagers until Year 9 and access to social media until two years later.
More schools are due to take part in the experiment in the coming months and a summit involving teachers from schools across Kent is to be held in September to discuss a cross-county approach to smartphones.