"Regarding our SNS usage measures, we find no significant differences in GPA by SNS user typology, nor types of social activities performed on these sites. This is understandable as social practices could both support (e.g. offer help with homework) and detract from (e.g. offer alternatives to focusing on school obligations) academic work, and thus their effects could cancel each other out. In contrast to uses specific to SNSs, we do find a positive association between Internet skills and academic achievement even when controlling for various demographic characteristics. The positive relationship between webuse skills and GPA may illustrate that students who have better online skills can draw on their Internet savvy to aid in their schoolwork. But engaging more intensely with SNSs, in particular, shows no relationship to our outcome variable of academic achievement."
Hargittai, Eszter and Hsieh, Yu-li Patrick (2010) Predictors and consequences of
differentiated practices on social network sites. Information, Communication & Society, 13(4) 515- 536 doi: 10.1080/13691181003639866