Growing up on a farm in rural Wyoming in the 1980s, Sandra Roberts (a pseudonym) didn’t indulge in much screen time; after all, the only screen her family had was an old television that got four fuzzy channels, if the wind wasn’t blowing.

But one weekend, she was allowed to watch the entire three-movie Indiana Jones series with friends. When her mother arrived to pick her up, she found Sandra crying hysterically, complaining of a pounding headache and severe nausea. They went to the ER, but multiple tests showed nothing. The doctor finally suggested that Sandra might be overstimulated from six hours of nonstop action-film viewing, so he suggested having her do it again the following weekend as an experiment. Sure enough, the symptoms returned, this time after only three hours.

It was fairly simple for Sandra to avoid screens after that; besides, she says, she was too busy going to school, hanging out with friends and helping on the farm. Now, though, her 8-year-old son, Oliver, is having the same issues.

“He’s extremely far-sighted,” she says, “and screens allow his eyes to fixate and not move. That’s not good for anyone, but especially for him. It creates a hypnosis effect. After watching too much TV, he’s in tears, just like I used to be.”

So, Roberts and her husband introduced screen-time rules, allowing Oliver only an hour per day with any type of screen after finishing his homework and chores. But monitoring screen time is more difficult now than when she was younger, she says, because multiple screens are everywhere. And, she adds, “it’s difficult to tell him ‘no screen time’ when he sees me working on the computer.”

Adults today own an average of four devices with screens. According to a 2016 Nielsen report, they spend 10 hours and 39 minutes per day staring at those screens, an increase of a full hour over the previous year. The National Institutes of Health estimates that children’s screen time averages five to seven hours per day, including about three hours watching TV. The statistics change quickly as new devices appear in stores, as technology advances and as more and more schools and workplaces rely on screens.

As with every hot-button issue, however, there are two sides to the digital-world debate.