Loneliness is about more than just being alone, and it’s a larger problem than you might think.

When Vivek Murthy, the author, was appointed the 19th surgeon general of the United States, he had some clear ideas about what he wanted to tackle: mental health , obesity , and the opioid crisis.

But he also wanted to understand people’s own priorities. So after his appointment, he traveled across the United States on a listening tour. And his conversations showed that issues like obesity and the opioid crisis were indeed priorities, but something else came up time and again. From town halls in Alabama to community meetings in North Carolina, the subject of loneliness cropped up almost every time. 

It became clear to Murthy that in society today loneliness is a real problem.

The key message here is: Loneliness is about more than just being alone, and it’s a larger problem than you might think.

One cold Oklahoma morning, Murthy was listening to Sam and Sheila, a couple who’d lost their son to opioids. They explained that the pain they felt at his death was made even worse by loneliness. All through their lives they’d been part of a community, but now their neighbors ignored them. Assuming Sam and Sheila would be ashamed of how their son had died, nobody stopped by.

On another day, in Los Angeles, a successful executive admitted that he had just spent his birthday alone. The intensity of his work schedule had led him to lose touch with friends.

Murthy’s findings are anecdotal, but they’re supported by science. Loneliness is widespread. According to a 2018 study by the US organization AARP – which advocates for people as they age – 22 percent of American adults report being socially isolated, either often or always. This is the case all over the world. A quarter of Australian adults report loneliness, while in Japan more than a million adults meet the official definition of hikikomori, or social recluses.

So what exactly is loneliness? Well, it’s not just being alone; it’s the sense that you’re lacking the connections you need.

Researchers have identified three clear strands: Intimate loneliness is the longing for a partner with whom you share a deep bond. Social loneliness is the need for quality friendships. Finally, collective loneliness is the yearning for a community or network of like-minded people.

We need all three types of connection to thrive. And as we’ll see in the next blink, if you lack one or more, it can be painful – to the extent of seriously harming your health.