A survey released in Taiwan found that the time adolescents spend connected online approaches the weekly working hours of adult employees. Counted alongside school hours and sleep, a substantial share of the day is spent in front of a screen.

Much of that time is concentrated in short video, messaging and games, the survey found. It also noted the difficulty of separating study-related use from entertainment in the totals.

Researchers stressed that how the time is used matters more than the total. Aimless infinite scrolling and use immediately before bed have the largest effect on sleep quality.

Schools are divided over phone storage policies. More schools now collect handsets during class, though some parents object, citing commuting safety and emergency contact.

Chinese-heritage households face an added language dimension. Where the language of online content differs from the language spoken at home, parents find it harder to know what their children are consuming — a point raised repeatedly in counselling settings.

The researchers suggested that setting time windows is more practical than prohibition. Keeping devices out of the bedroom for the hour before sleep is, across multiple studies, the measure with the clearest effect.