Actual results may vary
The study, published last week in Computers in Human Behavior, analyzes 1,839 college students' survey data about Facebook use and actual grades (as opposed to self-reported grades). It also takes into account students' high-school GPAs.
On average, students say they spend 106 minutes on Facebook per day. Each increase of 93 minutes beyond 106 minutes correlates with a GPA decrease of .12 grade points -- statistically significant, but not dramatic when applied to a real-world situation.