A Scottish boarding school once attended by King Charles III has banned the use of mobile phones within the school.
Pupils at Gordonstoun are expected to leave their phones in their boarding houses during the day as well as handing them into staff overnight.
The school said it was concerned about the "addictive" nature of mobiles.
The new policy extends previous limits on phone use which are said to have boosted exam results.
Lisa Kerr, principal of Gordonstoun, said: "Asking children to have a phone in their pocket but not respond when it buzzes with a notification is like putting a bowl of M&Ms on their desk and asking them not to take one, even when no one is looking.
"We only need to ask ourselves how hard we find it not to pick up our own phone, to understand how much harder it will be for a teenager whose pre-frontal cortex brain has not fully developed sufficient self-regulation."
There is a slight exception for sixth year students who are allowed to keep their phones with them, as long as they are switched off during the school day.
In 2017, the school introduced a policy limiting the use of mobile phones during the school day.
The school reported an improvement in concentration levels and socialisation between pupils following this move, which it said contributed to improved exam results.
Ms Kerr continued: "Teenagers may argue that it's their right to have their phones. But we don't allow them unfettered access to other addictive substances, so why mobiles?
"I believe it's lazy, irresponsible, and dangerous not to place controls on young people's access to an online world which they, and we, simply don't fully understand and can't control.
"We want children to engage in real, not virtual relationships; we want them to hear the birdsong around them rather than music through their Airpods and we want them to be safe from algorithms which promote hate and harm."
Students are said to be supportive of the new policy, with one pupil stating they were "apprehensive" at the thought of being without a phone at first but are now happy to follow the rules.
Another added the policy has made an "instant impact", with more socialisation and productivity.
In July, the United Nations issued a warning about the risk of smartphone use in schools.
The report stated children should not be shielded from technology completely but more guidance was needed about what devices should be allowed in schools.