A comprehensive (and reader-friendly) overview of the psychological and medical research on "loneliness" by Judith Shulevitz in the New Republic. One example:
Back in the mid-’90s, when [psychologist John] Cacioppo was at Ohio State University (he is now at the University of Chicago), he and his colleagues sorted undergraduates into three groups—the non-lonely, the sort-of-sometimes lonely, and the lonely. The researchers then strapped blood- pressure cuffs, biosensors, and beepers onto the students. Nine times a day for seven days, they were beeped and had to fill out questionnaires. Cacioppo also kept them overnight in the university hospital with “nightcaps” on their heads, monitoring the length and quality of their rest. He took saliva samples to measure levels of cortisol, a hormone produced under stress.As expected, he found the students with bodily symptoms of distress (poor sleep, high cortisol) were not the ones with too few acquaintances, but the ones who were unhappy about not having made close friends. These students also had higher than normal vascular resistance, which is caused by the arteries narrowing as their tissue becomes inflamed. High vascular resistance contributes to high blood pressure; it makes the heart work harder to pump blood and wears out the blood vessels. If it goes on for a long time, it can morph into heart disease. While Cole discovered that loneliness could hasten death in sick people, Cacioppo showed that it could make well people sick—and through the same method: by putting the body in fight-or-flight mode.
Read the full piece here.
