An expert has sent out a stern warning to those addicted to social-networking: you could be jeopardising your own health by reducing levels of actual interpersonal contact.
According to Dr Aric Sigman, the sites, which are meant for enriching social lives, end up keeping people apart.
Lack of "real" social networking, involving face-to-face interaction, may have wide-ranging biological effects, he argued.
Sigman, who is a Fellow of the Royal Society of Medicine and Associate Fellow of the British Psychological Society, said evidence suggests that spending hours on such sites could alter the way genes work, upset immune responses, hormone levels and the function of arteries, and influence mental performance, reports Sky News.
Sigman issues the stark warning in the latest issue of Biologist, the journal of the Institute of Biology.
The doctor said: "A quarter of British children have a laptop or computer in their room by the age of five and they have their own social networking sites... It's causing huge changes."
He said: "When we are 'really' with people different things happen. It's probably an evolutionary mechanism that recognises the benefits of us being together geographically."