A new study has found that loneliness spreads very much like a communicable disease. It’s more than just unpleasant for those who yearn to be surrounded by warm relationships—it is a health hazard and the mere perception of being isolated is more than enough to affect our health.
Once one person in a social network started expressing feelings of loneliness, others within the same network would start to feel the same way. The effects spread as far as three degrees of separation. Those who had immediate contact with lonely people were around 50% more likely than average to feel lonely themselves. In people who knew people who had direct contact with lonely people, the figure was 25%. Those with three degrees of separation showed roughly a 10% increase."