Dr. Richard S. Schwartz, a Cambridge psychiatrist who has studied the problem of loneliness in America, notes that over four decades of studies have shown the devastating consequences of loneliness. Loneliness has been linked to an increased risk of cardiovascular disease and stroke and the progression of Alzheimer's. One study found that it can be as much of a long-term risk factor as smoking. In 2015, a huge study using data from 3.5 million people collected over 35 years, found that those who fall into the categories of loneliness, isolation, or even simply living on their own see their risk of premature death rise 26 to 32 percent.

But Schwartz also concludes that many people have a hard time admitting that they are lonely. He says, "Admitting you're lonely feels very much like admitting you're a loser. Psychiatry has worked hard to de-stigmatize things like depression, and to a large part it has been successful. People are comfortable saying they're depressed. But they're not comfortable saying they're lonely, because you're the kid sitting alone in the cafeteria."