From The New York Times:
They do it late at night when their parents are asleep. They do it in restaurants and while crossing busy streets. They do it in the classroom with their hands behind their back. They do it so much their thumbs hurt. Spurred by the unlimited texting plans offered by carriers like AT&T Mobility and Verizon Wireless, American teenagers sent and received an average of 2,272 text messages per month in the fourth quarter of 2008, according to the Nielsen Company — almost 80 messages a day, more than double the average of a year earlier. 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.
Dr. Martin Joffe, a pediatrician in Greenbrae, Calif., recently surveyed students at two local high schools and said he found that many were routinely sending hundreds of texts every day. “That’s one every few minutes,” he said. “Then you hear that these kids are responding to texts late at night. That’s going to cause sleep issues in an age group that’s already plagued with sleep issues.” The rise in texting is too recent to have produced any conclusive data on health effects. But Sherry Turkle, a psychologist who is director of the Initiative on Technology and Self at the Massachusetts Institute of Technology and who has studied texting among teenagers in the Boston area for three years, said it might be causing a shift in the way adolescents develop.
“Among the jobs of adolescence are to separate from your parents, and to find the peace and quiet to become the person you decide you want to be,” she said. “Texting hits directly at both those jobs.”