"Christakis likened it to sitting on a quilt of humanity, with each person sitting on a different-coloured patch that is connected to the next one. 'Imagine that these patches are happy and unhappy patches. Your happiness depends on what is going on in the patch around you,' Christakis said. 'It is not just happy people connecting with happy people, which they do. Above and beyond, there is this contagious process going on.' Each happy friend boosts your own happiness by nine per cent, the researchers suggest. On the other hand, having grumpy friends decreased the chances by about seven per cent. As for why, happiness is known to produce fewer stress hormones, said Andrew Steptoe, a professor of psychology at University College London who was not involved in the study. The study was conducted before the rise of online social networking sites such as Facebook and MySpace, but Christakis speculated the sites might support emotional contagion." - 'Joy to the world is contagious: study', cbc.ca, 4 Dec 2008.