We know smoking and obesity are bad for our health, but now scientists have discovered something that could be even worse: loneliness.

Researcher John Cacioppo from the University of Chicago says a sense of isolation or rejection can lead to a whole host of ailments including high blood pressure and an increased risk of Alzheimer’s Disease.

Cacioppo, one of the founders of a new field called “social neuroscience,” said the stress from being lonely makes it harder for blood to flow through the cardiovascular system, affects the immune system, and often makes it harder to sleep well.

Healthwise, he said the difference between a lonely person and a popular person was akin to “a smoker and a non-smoker,” something he called “stunning” and proof of “just how powerful it is.”

“The lonely have poor health,” Cacioppo said. “They exercise less [and eat] more fats and sugars … Loneliness lowers the ability to control yourself. It is really easy after a bad day to have a second scotch and a third to get some comfort.”

He said loneliness evolved as a prompt to action, signalling an ancestral need to repair our social bonds. But as conventional family structures have died out, the problem has grown.

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