Cervical spine surgeon K. Daniel Riew at Och Spine at New York-Presbyterian/Weill Cornell Medical Center has started seeing patients in their 20s. That age group rarely appeared in his practice before. Americans now average about seven hours a day on screens, according to DataReportal, and the physical body adapts to patterns that repeat.

A spine surgeon, a vision scientist, and a medical sociologist each described what that adaptation looks like. The findings are more specific than the general worry about screen time allows for, and several of them are at odds with standard advice.

What tech neck does to the spine

When the head tilts forward to look at a screen, the muscles at the back of the neck engage to hold it up. Ordinary soreness is the initial result. What matters more is what happens to the cervical discs under sustained, repeated load over years: premature cell death and accelerated degeneration. “Once enough cells have died, there is no going back,” Riew says.

Phones are harder on the neck than other screens because people manage them less deliberately. A monitor can be raised. A phone goes everywhere. Most people holding one at waist or chest height never think about cervical alignment, including those who have already rearranged their work setup because of neck pain.

The conventional advice to sit up straight at 90 degrees is, in Riew’s view, a setup for slouching. He recommends reclining at 25 to 30 degrees with lumbar support and a headrest, which shifts the weight of the head and torso into the chair rather than down through the spine. “I can sit in that position for hours without feeling any pain,” he says.

Why screens probably aren’t causing children’s myopia

Rates of myopia have climbed sharply among children. Screens take the blame by default. Donald Mutti, a vision scientist whose work on the CLEERE study (Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error) shaped the field, thinks that’s probably wrong. Screens may not be raising myopia risk directly. They are, however, keeping children inside, and outdoor time is what the data shows protects against nearsightedness.

A study using smartwatch data supported that picture. Two hours of outdoor time per day delivered the maximum protection against developing myopia. The outdoor time needed to last at least 15 minutes per outing, and the light needed to hit 2,000 lux, roughly four times standard office illumination. Shorter or dimmer exposure did nothing. “2,000 lux is easily obtainable outdoors, even in shade,” Mutti notes.

For adults, he is largely unconcerned. “I don’t think there is much of any effect in adults beyond eyestrain. Moderation in all things is always good advice.”

What the grip strength decline tracks to

Grip strength, a well-established marker of overall muscular health and longevity, has been falling across the general population. Soft, screen-bound hands tend to get the blame.

Johannes Beller, a professor of medical sociology at Medical University Lausitz-Carl Thiem, pushed back on that in a 2019 study published in the peer-reviewed journal SSM. The team traced the decline to cohorts born well before smartphones existed. Whatever is driving it, the phone is not the only answer.

“Grip strength is valuable precisely because it reflects overall strength and health, not because the hands themselves are the target,” Beller says. “Staying active and strong is something almost anyone can act on, at any age.”