The Economist:

France has not allowed smartphone use in primary or secondary schools since 2018, claiming that it would help children focus, reduce their social media use and mitigate online bullying. The Netherlands initiated a similar ban in January 2024. Hungary followed suit later that year. Legislators in Britain are considering similar measures. The key question facing them is whether banning smartphones in schools offers any benefits to mental health.
That there is a problem seems clear. In 2021 America’s surgeon general compiled a report revealing that persistent feelings of hopelessness climbed by 40% among American high-school students between 2009 and 2019. The number who seriously considered killing themselves went up by 36%. What makes these findings all the worse is that 48% of mental-health problems (like depression and anxiety) that emerge during adolescence will plague people for the rest of their lives.