As a doctor, Dhruv Khullar sometimes spends the last moments with his patients, the only one at their bedside with no friends or family to notify about their impending passing.
In the weeks leading up to that moment, he's seen the same patients lying alone in their beds, the TV blasting an old game show rerun; it's the same monotonous routine of boredom and isolation playing out without a visitor for days or even weeks at a time.
"What really drew my attention to the issue and why I felt so strongly about writing about it is the way people are struggling with it on the ground level. That's something I experience everyday," he said.
These scenes led Khullar to wonder if loneliness was literally killing his patients, a driving force of their premature death. He quickly found social isolation is a growing epidemic.
According to a 2013 study by the AARP, the percentage of American adults who say they're lonely has doubled since the 1980s, rising from 20 to 40 percent. Nearly a third of Americans older than age 65 live alone. That number jumps to 50 percent for those over age 85. Other disorders also contribute to the trend, including social anxiety and depression.
"The numbers are pretty staggering on just how many people deal with loneliness and social isolation in our country," Khullar said. "And increasingly I think what we're recognizing in the medical community is all the negative physical, mental and emotional consequences that this kind of isolation can have."
Perhaps even more shocking than the number of Americans who say they're lonely are the resulting health consequences.
"There's been studies that have shown that loneliness can actually be as big a risk factor for premature death as things like obesity and smoking, which we typically think a lot about in the public health spheres," Khullar said.
The doctor said poorer sleep patterns, more inflammation in the body, increased levels of stress hormones and disrupted immune systems might contribute to why we're seeing such drastic effects.
Khullar added one epidemiology study that pooled data from dozens of organizations and millions of people across the globe found those who suffer from social isolation are up to a third more likely to die within the next decade.