According to a University of Wisconsin study, despite frequent claims to the contrary, when it comes to depression, the answer's no:
Despite all its merits in keeping people connected, Facebook has been suspected of leading to unfortunate side effects, such as jealousy, low self-esteem or divorce. But new research out of the University of Wisconsin suggests people should think twice before tacking depression onto that list.
"People have looked at things like jealousy, and more transient moods or whatnot, but we really looked at clinical depression," Lauren Jelenchick, the lead author of the study, told The Huffington Post. "There was no relation between the amount of time [study participants] were on Facebook and their symptoms of depression"
On the other hand, a study from the University of Salford in the U.K. indicates that social media may cause anxiety and lower self-esteem:
About half of the survey’s 298 participants, all of whom identified themselves as social media users, say that their use of social networks like Facebook and Twitter makes their lives worse. In particular, participants noted that their self-esteem suffers when they compare their own accomplishments to those of their online friends.
In addition to confidence issues, two-thirds claim they find it difficult to fully relax or sleep after spending time on social networks. A quarter cited work or relationship difficulties due to online confrontations. And more than half say they feel “worried or uncomfortable” at times they are unable to access their Facebook or email accounts.