Nepal, July 8 -- There was a time when one of the world's greatest civilisations, China, lost an entire generation to a slow, silent poison: opium. It numbed pain, dulled ambition and emptied futures. Young Chinese people who might have become poets, scientists, or leaders spent their days staring into the smoke. By the time the nation realised the damage, it was too late.

Today, as I walk through school corridors or sit with concerned parents, I fear we are on a similarly dangerous path-only now, the poison glows in the palms of our children's hands. It's more innocuously called a handheld device (phones, tablets, etc.) We see its impact every day. Children can barely sit through a conversation without reaching for a screen. Playgrounds...