This week the internet has been flooded with news reporting a study done by Ohio State University It scientifically and measurably shows the effects of loneliness on the human immune system. From what I have read, it seems to be a very well done study and the results are compelling. Here's part of an article that I read with a couple of links to more information:
..."It is clear from previous research that poor-quality relationships are linked to a number of health problems, including premature mortality and all sorts of other very serious health conditions. And people who are lonely clearly feel like they are in poor-quality relationships," said Lisa Jaremka, a postdoctoral fellow at the Institute for Behavioral Medicine Research at Ohio State University and lead author of the research. "One reason this type of research is important is to understand how loneliness and relationships broadly affect health. The more we understand about the process, the more potential there is to counter those negative effects – to perhaps intervene. If we don't know the physiological processes, what are we going to do to change them?"