In September 2008, when Nielsen Mobile announced that teenagers with cellphones each sent and received, on average, 1,742 text messages a month, the number sounded high, but just a few months later Nielsen raised the tally to 2,272. A year earlier, the National School Boards Association estimated that middle- and high-school students devoted an average of nine hours to social networking each week. Add email, blogging, IM, tweets and other digital customs and you realize what kind of hurried, 24/7 communications system young people experience today.

Unfortunately,...