Facebook use can lead to symptoms of depression if the social networking site triggers feelings of envy among its users, research shows. "Facebook can be a fun and healthy activity if users take advantage of the site to stay connected with family and old friends and to share interesting and important aspects of their lives," an author said. "However, if Facebook is used to see how well an acquaintance is doing financially or how happy an old friend is in his relationship--things that cause envy among users--use of the site can lead to feelings of depression."