All that frenzied texting may be causing undo stress for teens. Researchers in Sweden found that young people ages 15 to 20 who made more than 15 calls and sent more than 15 messages per day suffered from stress, restlessness and sleep problems. Study leader Dr. Gaby Badre, from Sahigren's Academy in Gothenburg, said: "Addiction to cell phones is becoming common. Youngsters feel a group pressure to remain interconnected and reachable round the clock. Article