Researchers at Harvard University have discovered a link between loneliness and the levels of a blood-clotting protein that can cause heart attacks and stroke. Social isolation is known to activate the “fight or flight” stress signal, which increases levels of the protein fibrinogen in anticipation of injury and blood loss. Too much fibrinogen is bad for health, raising blood pressure and causing the build-up of fatty deposits in the arteries. The study concluded that having no friends has the same impact on protein levels as smoking. Social connectedness requires seeing friends at least twice a week.
