Always envious? Got a non-existent social life and struggle to concentrate? All this might be down to Facebook if you believe a study showing those who go a week without using the social network feel happier than others.

Carried out by the Happiness Research Institute, the study involved a sample of 1,095 people in Denmark who were

divided into two groups, half of whom continued using Facebook while the others stopped.

"We focused on Facebook because it is the social media that

most people use across age groups," Meik Wiking, HRI's chief executive told AFP Tuesday in Copenhagen, the Danish capital.

After a week, those people who hadn't been on Facebook said they were more satisfied with their lives, with 88 percent of them describing themselves as "happy" compared with 81 percent from the second group. Facebook users are 39 percent more likely to feel less happy than non-users, the study says.