Are you between the ages of 23 and 38? Are you lonely? According to a new survey by YouGov, if you answer yes to the first question you're much more likely to answer yes to the second.

YouGov surveyed 1,254 Americans over 18 about friendship and loneliness, and, at 30 percent, Millennials were the most likely age cohort to say they felt lonely "often" or "always." By contrast, 20 percent of Gen-X respondents said they felt lonely often or always, and only 15 percent of Baby Boomers gave those answers.

Millennials were also the most likely to report having zero friends (22 percent), zero close friends (27 percent) and zero acquaintances (25 percent). Although that last statistic makes you wonder how respondents were defining acquaintances. Only 9 percent of the much-less-isolated Baby Boom cohort reported having no friends or no acquaintances. YouGov did not break out numbers for Generation Z, those under 23, perhaps because there were fewer of them in the sample. So, at least for now, Millennials hold the dubious distinction of being our nation's loneliest generation.

Why are Millennials so lonely? YouGov did not ask respondents to explain their loneliness, and in any case it's a question many lonely people can't answer. But YouGov data scientist Jamie Ballard noted in her report on the findings that other studies have decisively linked heavy social media and internet use with both loneliness and depression. She and other observers concluded that Millennials, who use both social media and the internet more frequently than their elders, are making themselves lonely in the process.

That certainly could be part of the explanation, but I suspect it's not all. For one thing, many professionals spend the years right after college hyper-focused on their careers. Also, people in their 20s and 30s are often deeply involved in romantic relationships or are raising children. (Respondents were specifically told to exclude their partners and families when answering questions about their friendships.)

Or, it may be that Millennials are the first generation raised with schedules that included plenty of extra-curricular activities and little free time, something that's become more normal with every new generation. Making and maintaining friendships requires spending time, and if you feel like every waking moment must be filled, that can be difficult.

Or it may be popular culture setting unrealistic expectations. People in their 20s and 30s are invariably portrayed as very social, pictured in large groups of friends--the kind of friend groups that make the rest of us envious--laughing in bars or playing beach volleyball. From The Big Bang Theory to New Girl, we've been shown over and over that Millennial lives are supposed to be full of friendship. So it seems to me that if you're that age cohort and you don't eat a takeout dinner surrounded by half a dozen pals every night, you might start feeling like there's something wrong with you.

Maybe it's a lonely time of life.

It could also just be a life-cycle thing. In 1990, before many Millennials were born, social psychologist Daniel Perlman undertook a meta-analysis of 14 loneliness studies with over 25,000 respondents. Even back then, before the existence of smartphones, social media, and even before internet use was widespread, he found that young adults were the likeliest to be lonely, with loneliness decreasing throughout people's lives until they reached old age, when it increased moderately. That aligns with my own non-scientific observation that people in their 50s and 60s--most of whom are either retired or planning retirement, and whose grown children are mostly out of the house--are more likely to gather in friend groups than other age cohorts.

Whatever the explanation for Millennial loneliness, it would be a mistake to ignore it. There's plenty of evidence that loneliness and isolation are seriously bad for your health, whereas those who live surrounded by friends have increased longevity. Survey respondents who said they had trouble making friends were asked why that was. Some said they were too busy, friendships took too much work, or that they didn't need more friends. But more than half gave this simple reason: "I'm shy."

That's a shame, because if you're feeling lonely and that you'd like to have more friends, it's a certainty that some of the people you encounter in your daily life feel the same way. And possibly some people that you used to know would love to hear from you again. Reaching out to make new friends or get back in touch with old ones can feel like the most difficult thing in the world if you're feeling lonely and down. But chances are, if you can do it, the people you reach out to will be happy and grateful that you did. It could even add years to your life.