Loneliness link
In the survey, participants answered questions about how they felt, how worried they were, how lonely they felt at that moment, and how much they had used Facebook since the last survey.
They received five text messages each day at random times between 10:00 and midnight, containing links to the surveys.
Researchers also wanted to know about how much direct interaction participants had with people - either face-to-face or by phone - between questionnaires.
Results showed that the more people used Facebook, the worse they felt afterwards. But it did not show whether people used Facebook more or less depending on how they felt, researchers said.