Researchers at the University of Chicago have found that loneliness can lead to a number of adverse health effects, including higher blood pressure, worse sleep habits, and obesity.

The leader of this research was John Cacioppo, a professor for the Department of Psychology and the director of the Center of Cognitive and Social Neuroscience. He has had numerous papers on loneliness published in *Perspectives on Psychological Science*, the *Annual Review of Psychology*, and the *International Encyclopedia of Social and Behavioral Sciences*. His most recent paper on loneliness, “Loneliness Across Phylogeny and a Call for Comparative Studies and Animal Models” was published in 2015 and examined how physical responses to feeling lonely present themselves in animals.

In a prepared statement, Cacioppo wrote, “Millions of people suffer daily from loneliness, a debilitating psychological condition characterized by a deep sense of emptiness, worthlessness, lack of control, and personal threat.”

What Cacioppo describes as loneliness, however, is more than just isolation. He classifies being lonely as feeling like one cannot connect with others, even if one is not technically alone. He states that people can be lonely even if they are surrounded by friends and family.

Cacioppo’s research connects many of the physical effects brought on by loneliness to the basic evolutionary needs of humans as social animals.

“Loneliness has been linked to poor immune functioning, elevated blood pressure, higher levels of circulating stress hormones, poorer sleep quality, poorer executive functioning, obesity, alcoholism and drug abuse, even dementia in older adults,” Cacioppo said in an interview with Jeannette Rijks for the Dutch website *Eenzaamheid Informatie Centrum*, which translates to “Loneliness Information Center.”

According to Cacioppo, when people feel isolated, their brains revert to a mode of self-preservation that exhausts the system and prevents bodies from resting properly.

By studying Rhesus monkeys, researchers discovered that loneliness can also affect the development of white blood cells, called monocytes. Lonely people release fewer mature cells into the bloodstream that are better equipped to deal with bacteria, whereas the more mature cells found in non-lonely people are more mature and prepared to battle viruses. Cacioppo attributes this difference to varied evolutionary needs, as a lonely person would be more likely to deal with physical wounds and less likely to be around viruses, which are spread from person to person.

Feeling lonely can be a self-fulfilling cycle when it comes to social interaction. Lonely brains are hyper-alert for negative social cues, which makes normal interactions seem hostile and prevents them from reaching out and forming genuine connections with others.

“The self-preservation mode can promote short-term survival but, paradoxically, it can also make forming new salutary relationships more difficult,” Cacioppo wrote.

There are ways to break this cycle. Cacioppo has developed a 4-step system represented by the acronym “EASE.” Under this system, a lonely person should “extend themselves” by trying new things, make an “Action Plan” that commits to doing so, “select” people with whom they can build positive and meaningful relationships, and generally “expect the best” from their efforts.