Nearly three out of four teenagers in the United States say they feel happy or peaceful when they do not have their smartphone with them, a survey has found. However, only 36 percent of teens reported cutting back on using their devices, the survey by the Pew Research Centre showed. Overall, 38 percent reported spending too much time on their smartphone, compared with 51 percent who said their time spent was “about right,” with girls more likely than boys to consider their use excessive.