Spending too much time on social networking sites makes teenagers prone to vain, aggressive, and anti-social behavior.

That's according to a psychology study by a professor at California State University.

"While nobody can deny that Facebook has altered the landscape of social interaction, particularly among young people, we are just now starting to see solid psychological research demonstrating both the positives and the negatives,” researcher Larry D. Rosen said in an address to the 19th Annual Convention of the American Psychological Association.

More of those negatives include increased episodes of anxiety, depression and poor grades, according to a report from The Daily Telegraph.

But the study shows the effects of social networking sites like Facebook aren't all bad. Actually, Rosen said these websites offer a platform to shy young adults where they can come out of their shells more comfortably and they also serve as a space for teenagers to empathize with others and learn from each other.