According to a new report by the Nielsen Company, teenagers in the U.S. sent an average of 2,272 text messages per month. That comes out to more than 80 messages per day, representing a more-than 100% increase compared to the year-ago quarter.It's hard to say if the real winners here are the teens or the wireless companies. Sure, teens are milking the living daylights out of those unlimited messaging plans, but they are doing it at a cost -- at least, so say doctors.

The New York Times posted an in-depth piece today about the health consequences of cosntant messaging. It reports, "The phenomenon is beginning to worry physicians and psychologists, who say it is leading to anxiety, distraction in school, falling grades, repetitive stress injury and sleep deprivation."

I can sure attest to the repetitive stress injury part of the equation. Back when I was using a BlackBerry, there would be days when the tendons attached to my thumbs would ache and burn. It was known as "BlackBerry Thumb", stress and fatigue of the repetitive motion of typing on a BlackBerry.

In all honesty, I haven't had any problems since I switched to using an iPhone most of the time for messaging. Why? Well, with a physical keyboard, you have to press each key to get it to respond. With the iPhone (and many other touch phones), you simply touch the screen lightly to get the same result. You don't have to exert any real pressure.

I've never sent or received as many messages per month as the average U.S. teen, but I've come awfully close.

The Times article includes a lot of other good information about not only the physical issues that texting can bring up, but also the psychological issues, such as dependence and development. If you're the parent of a teen, I highly suggest you give it a read.

If you're the busy manager of younger employees who you've armed with BlackBerries, you can probably get something out of it, too.

The end story is that anyone in charge of a messaging device needs to keep track of how it is being used.