Imagine the latest must-have item for kids was addictive and had a proven link with disrupted sleep, depression, low self-esteem and attempted suicide. You certainly wouldn’t buy one for your own offspring, but you might think banning it altogether was a step too far. That is, until your child comes home from school begging to have one, just like their friends.

You may not have to imagine much longer. There is increasing evidence that such a product already exists and is wildly popular. It’s called a smartphone. Perhaps the most persuasive evidence yet is a paper published last month in the journal Clinical Psychological Science, based on a study of more than half a million American adolescents over five years. A team led by the psychology professor Jean M Twenge found that kids who used their smartphones for three hours or more a day were one-third more likely to feel hopeless or consider suicide, rising to nearly half of those who used such devices for five or more hours a day. Simply using social media daily was linked with a 13% higher incidence of depressive symptoms.

If this finding is replicated, the new French ban on kids from using their mobile phones at school will not be criticised for being over the top, but for not going far enough. A compelling case for completely banning kids having smartphones is a handful of scientific studies away.