You already know a lot of good reasons you shouldn't constantly use your smartphone. Using them at night interferes with sleep, using them for too much social media can lead to mental health issues for young people, and one study even showed that having our smartphones nearby all the time leads to reduced cognitive function

Well, here's a new concern for both yourself and your children: Too much smartphone use might possibly alter the bone structure of your skull, new research reveals. It could possibly cause pointy protuberances to grow on either side of the base of the skull--what the Washington Post and others call "horns." There's no need to worry that you'll wind up looking like Hellboy--for one thing, x-rays show this new bone growth points down, not up. But there's plenty of reason to worry about the long-term effect constant smartphone use is having on your skeletal system and your skull. It might be especially harmful to today's children who sometimes start playing with smartphones or tablets before they're out of diapers.

A research team led by David Shahar, of the School of Sport and Health Sciences, University of the Sunshine Coast, Queensland, Australia, analyzed 1,200 x-rays of people ranging in age from 18 to 86. It's worth noting that these x-rays were obtained (without patient names or identifying information) from a local chiropractic office, which suggests that they had some reason to be concerned about their spinal alignment. Still, half the subjects were reporting no symptoms when the x-rays were taken.

The researchers were surprised to see the protuberances--formerly highly unusual--on 33 percent of the subjects' x-rays. But what was truly surprising was this: The younger the subject, the likelier he or she was to have these bone growths. The researchers had previously found that these growths, called enthesophytes, appeared to exist in 41 percent of 18-to-30-year-olds. "These findings contrast existing reports that large enthesophytes are not seen in young adults," the researchers wrote.

Generally speaking, extra bone growth appears on bones and joints that are under extended unusual stress, usually over many years. That's why they tend to appear on middle-aged or old people, not young ones. They particularly tend to appear when weight is repeatedly placed on a bone or joint in an unnatural way--the bone growths are the body's attempt to better support that weight. In other words, the researchers think, the bone growths may result from people holding their heads bent forward frequently and for long periods of time while using their smartphones. They suspect that they're more likely to appear on younger people because younger people, on average, spend more time using their smartphones than older ones do.

As naysayers are quick to point out, there's a very big difference between correlation and causation, and without knowing the identities of any of the subjects there's no way to ask them about their smartphone habits. It's certainly true that other types of activities, such as reading, can cause people to bend their heads in the same way and might possibly account for the enthesophytes. The problem with that explanation, though, is that older people have most likely spent more time reading than younger ones, not less. So it doesn't make sense that younger people would be likelier to have the bone growths. That fact supports the researchers' preliminary conclusion that smartphone use is the culprit, although obviously further study is needed to confirm that this is true and to figure out exactly how it happens.

You can check for yourself.

In the meantime, what should you do? You could begin by checking to see if you have these bone growths yourself. If you do, you might well be able to find them if you feel around the base of your skull. (Take a look at the x-rays the researchers have published to get a good sense of exactly where they'd be.) If you do find them, there's no need to panic. Many of the subjects who had the bone growths were reporting no symptoms, and indeed, the researchers note, many of us develop bone growths in other parts of our bodies as we age without being particularly bothered by them. But since--until now--it's been uncommon for young people to have them, it's difficult to know what effect they might have, if any, over the many decades younger generations have ahead of them.

Whether or not you have enthesophytes already, it's likely a good idea to change how you use your smartphone or tablet to avoid bending your head over it whenever possible. If you have children or young friends or relatives who spend many hours bent over their smartphones, it's particularly important to try and get them to change how they use those devices. 

Or, you could get them to take a walk, go to a movie, have a real-life conversation, attend a concert, or do any number of things that require them to set aside their smartphones. Given how harmful those devices can be--even if you're not growing "horns"--it's always a good idea to try using them a little less.