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Loneliness stinks. We've probably all been there at one time or another, and there's no really arguing with the fact that it is no fun.

But it turns out that loneliness might have an even nastier set of tricks up its sleeve:. It could be wreaking havoc on our health and even cutting short our lives. Um... what?

The Internet is full of headlines about how dangerous loneliness can be, but the idea that it causes more public health problems than obesity or that it can literally kill you is pretty wild. Thankfully, things might not be quite as dire as a Google search might lead you to believe… but it is worth taking a look at how loneliness can affect your health. It's important to realize that loneliness isn't the same as social isolation, which is the state of being out of contact with society or other people.

Living alone or spending lots of time by yourself isn't bad, as long as it works for you. Loneliness is more about the psychological consequences of having a gap between the interaction and social support you'd like and what you're actually getting. When you think about it, loneliness is actually a pretty sensible thing, evolutionarily-speaking.

Psychologists have suggested that it could fulfill a role similar to hunger, urging us to seek out the kind of social companionship that helps us survive and pass along our genes. But it can become kind of problematic when it stops being a short-term thing—like after a move to a new city—and becomes a long-term one. Now, the stats on how many of us struggle with loneliness are honestly all over the place.

But many studies have shown that rates are highest among adolescents, and some have suggested that loneliness becomes more prevalent again very late in life. Recent surveys in the UK, Australia, and New Zealand have suggested that about 10-30% of adolescents and young adults and about 10-15% of the elderly experience persistent loneliness. One study even suggested that loneliness can be contagious.

In other words, how lonely your friends and neighbors are can predict your future loneliness, maybe because lonely people tend to pull away from others. So, you know, that's great. Even though it might be hard to pin down exactly how common loneliness is, there's actually quite a lot of evidence that it's linked to a number of health problems.

It's been associated with higher levels of the stress hormone cortisol, higher blood pressure, and increased risk of heart disease. It's also been linked to lower activity in genes that reduce inflammation, and even to dementia. But in that case, it's not clear if loneliness causes the condition or if the condition itself causes loneliness.

Loneliness can also mean that the things we normally do to protect our health are less effective. For example, it can predict poorer sleep and make us less likely to exercise. A 2005 study of 83 college freshmen also found that the immune systems of the students with the highest levels of loneliness were less responsive to certain components of vaccinations.

And yes, there's even some evidence that loneliness is linked to dying sooner, although to be clear, the jury's still out on that one. Yeah, so that's a lot. But what could possibly make loneliness have such a powerful effect on us?

Right now, there isn't a lot of data looking at the same individuals over a long time, which makes it hard to say for sure. But the generally accepted hypothesis has to do with loneliness' ability to increase stress and shut down those protective health behaviors. The idea is that, in an evolutionary sense, social isolation is similar to being unsafe.

There's no one around to support or protect you, which would have been bad news for early humans, so it triggers all that fight-or-flight stuff. It activates the HPA axis, a system spread throughout your body that coordinates your stress responses and gets the cortisol pumping. This makes us hypervigilant to other social threats, which probably compounds the loneliness problem by making us not very nice to other people.

After all, CONSTANT VIGILANCE! never made Mad-Eye Moody many friends. Being on high alert all the time also takes away from our ability to control our behaviors. So goodbye gym, hello package of corn dogs!

Which, you know, I've heard is not great for your health, even if they are the best. The good news is that there has been a substantial bit of research done on how to counter loneliness and its effects. And thankfully, it's more helpful than just, like, “Go out and make some friends!

Go to the ... bar!” One meta-analysis found that group activities with an educational or discussion focus could reduce loneliness in older adults, and psychologists also recommend volunteering or doing good deeds for others. Or you could get a pet! Obviously we all know our pets our wonderful and perfect, but there's also legit research in older adults showing that animal-assisted therapy can reduce feelings of loneliness.

Even though the Internet often gets a bad rap, studies have also shown that chatting in forums can help, too. And other research showed that social media that's based around images and video offers more intimacy than text-based social media and can make you feel more connected to people. So, you know, just keep hanging out with us!

Loneliness is never fun, and it doesn't seem to be great for your body, either. But there are ways to get out of that slump. And at the end of the day, there's nothing wrong with seeking out professional help, too.

Thanks for watching this episode of SciShow Psych! People are wonderful and complicated, and if you've ever wondered why you are the way you are, we might have some answers for you. If you'd like to watch more episodes or stay up to date when new ones come out, you can go to youtube.com/scishowpsych to subscribe. [OUTRO ♪].