Texting teenagers who stay ‘on call’ all night pay the price in lost sleep Brookline 10th-grader Ashley Olafsson sleeps with her cellphone under her pillow so she doesn’t miss “emergency’’ texts — “like if a friend broke up with her boyfriend.’’ Stephanie Kimball of Waltham, 14, is also available for urgent overnight correspondence, such as, “Hey, seeing if you’re awake.’’ Dedham ninth-grader Courtney Johnson gets as many as 100 texts while in bed. “I just don’t feel like myself if I don’t have my phone near me or I’m not on it,’’ she said. Sure, all that middle-of-the-night communication leaves...