Facebook makes you unhappy? A controversial research

A few days ago, I saw an interesting article which was a warning about the usage of Facebook.
This is a research article published in PLOS One, a famous academic journal.

Facebook Use Predicts Declines in Subjective Well-Being in Young Adults

This article describes an experiment. Approximately 80 young participants were asked to use Facebook via iPad. They took some self-check tests for 2 weeks. The result is that the longer time they use Facebook, the less they are satisfied in daily life.

So, does Facebook cause unhappiness? As an academic article, the author made several remarks about the interpretation of the result. The finding was significant, but not so big that it is unclear whether this result can be generalized. We should be cautious to make a decision about this matter.

The authors suggested the relationship between the influence of using Facebook and direct social contact. According to them, people frequently contact with others via offline tend to be influenced negatively from using Facebook. This finding is difficult to understand. Is it possible that solitary people are immune to negative impact on Facebook?

I am also concerned about the characteristics of the participants. This article does not mention of whether the participants are accustomed to the internet or SNSs. I think that this experiment would be tough for beginners of these activities.
The term of the experiment may be too short to evaluate the influence of Facebook precisely. In my experience, it takes a couple of months to be familiar with this kind of services.

To begin with, why is Facebook harmful?
Perhaps you can imagine a hypothesis. Facebook and all any other SNSs can visualize our real life. If you try to hide your own activity, you have to see the daily activities of other people in the network society. Most people want to make themselves look bigger than the real. Thus, you would see a lot of people look like happy, perhaps compared to you. It annoys you. It makes you envious. Comparison to others is unhealthy in most situations.

This is a hypothesis. Of course, Facebook has much more advantages. I do not think that people should quit Facebook even if this study is correct. Nevertheless, it should be said that we have to investigate more in detail about the influence of social networking on our own mind and the society.