Surfing the net has become an obsession for many Americans with the majority of U.S. adults feeling they cannot go for a week without going online and one in three giving up friends and sex for the Web. A survey asked 1,011 American adults how long they would feel OK without going on the Web, to which 15 percent said a just a day or less, 21 percent said a couple of days and another 19 percent said a few days. Only a fifth of those who took part in an online survey conducted by advertising agency JWT between Sept 7 and 11 said they could go for a week. The poll, released on Wednesday, found the use of cell phones and the Internet were becoming more and more an essential part of life with 48 percent of respondents agreeing they felt something important was missing without Internet access. More than a quarter of respondents -- or 28 percent -- admitted spending less time socializing face-to-face with peers because of the amount of time they spend online. It also found that 20 percent said they spend less time having sex because they are online.