The NY Daily News, the Daily Mail, Computerworld, and the Huffington Post, among other outlets, covered Cornell research on (not) quitting Facebook.  The team surveyed people who took the "99 Days of Freedom" from Facebook pledge and analyzed the responses.

What makes quitting difficult for some?

1. When people *think* Facebook is addictive.
2. When people care who's watching
3. When people are not in good moods.
4. When people don't have other social networks to visit.

The paper can be found at: Missing Photos, Suffering Withdrawal, or Finding Freedom? How Experiences of Social Media Non-Use Influence the Likelihood of Reversion. Eric P. S. Baumer, Shion Guha, Emily Quan, David Mimno, and Geri Gay. Social Media and Society, 2015. 

http://infosci.cornell.edu/news/cornell-research-these-factors-might-explain-why-we-can-or-cant-quit-facebook