Few things delight children, or irritate their minders, as much as screen time.
Parents nag their offspring to put down their digital devices and pick up a book or a football.
Academics such as Jonathan Haidt worry that phones and social media are creating an "anxious generation" of indoorsy introverts.
Some countries are banning social media for under-16s.
The worry may be focused on the wrong age group.
For all the fears around teens and screens, the most square-eyed generation is the elderly.
Older people have long been champion tv-viewers.
Now a new generation of pensioners are adding to their screen time with smartphones, iPads and game consoles.
The result is epic screen sessions, which take up more than half of pensioners' waking hours.
The digitisation of old age is a good thing.
The elderly have perhaps more to gain from smart devices than any other age group.
Facebook and WhatsApp bring daily updates from old friends and faraway grandchildren.
Zoom transports church, book clubs and doctors' appointments into the home for people who cannot attend in person.
E-commerce removes the need to trek around shops.
Hours of entertainment from any era are available on demand.
A connected retirement is more fulfilling and fun than an offline one.
Older people are also insulated from some of the on-screen risks that threaten teenagers.
They have already formed their key real-life relationships,
and so are less in danger of the "social stunting" that screen-obsessed children supposedly suffer.
Their worldview is less open to manipulation by online weirdos who encourage misogyny or body dysmorphia among young folk.