Online gaming site Roiworld surveyed 600 teens ages 13 to 17 in late April and found that teens spend two hours per day online on average, 80% of which is spent using a social network. These same teens are, however, showing signs of "Facebook Fatigue." Nearly one in five (19%) who have an account no longer visit Facebook or are using it less.

Of the group that are saying goodbye to Facebook, 45% have lost interest, 16% are leaving because their parents are there, 14% say there are "too many adults/older people" and 13% are concerned about the privacy of their personal information.

The study also suggests that the teens that continue to stick to Facebook do so primarily to play games. Roiworld found that more than one-third of the teens who play games on Facebook admit to spending at least 50% of their time on the site immersed in gameplay. The online gaming trend extends far beyond Facebook, as 75% of surveyed teens claim to play games on the web.

Source: Mashable
http://mashable.com/2010/06/30/teens-social-networks-study/