If you are young and love Facebook, keep it to just "liking" and minimise your virtual circle of friends to cut the upcoming depression risk. According to researchers, the social networking site can have positive and negative effects on the levels of a common stress hormone in teenagers. The team found that having more than 300 Facebook friends increased teenagers' levels of cortisol while those who only posted "likes" on their Facebook friends to encourage them actually decreased their cortisol levels. "We were able to show that beyond 300 Facebook friends, adolescents showed higher cortisol levels. We can imagine that those who have 1,000 or 2,000 friends on Facebook may be subjected to even greater stress," explained Professor Sonia Lupien from University of Montreal. "While other important external factors are also responsible, we estimated that the isolated effect of Facebook on cortisol was around eight percent," Lupien noted. Lupien and her colleagues recruited 88 participants aged 12-17 years who were asked about theirFacebook use, number of friends, self-promoting behaviour, and the supporting behaviour they displayed toward their friends. Along with these four measures, the team collected cortisol samples of the participating adolescents. Other studies have shown that high morning cortisol levels at 13 years increase the risk of suffering from depression at 16 years by 37 percent. While none of the adolescents suffered from depression at the time of the study, Lupien could not conclude that they were free from an increased risk of developing it. "We did not observe depression in our participants. However, adolescents who present high stress hormone levels do not become depressed immediately; it can occur later on," Lupien emphasised. Some studies have shown that it may take 11 years before the onset of severe depression in children who consistently had high cortisol levels The study is one of the first in the emerging field of cyberpsychology to focus on the effects of Facebook on well-being. "Developmental analysis could also reveal whether virtual stress is indeed 'getting over the screen and under the skin' to modulate neurobiological processes related to adaptation," the authors noted in apaper published in the journal Psychoneuroendocrinology.