Social isolation isn't known to be great for the body.
Being alone a lot has been shown to increase everything from muscle tension to immune system issues — but it's feeling alone, rather than actually being isolated, that can have big impacts on psychological and physical health. So what happens to the brain when you're simply an introvert who likes chilling on your own? Interestingly enough, a whole host of neurological changes appear when you start to withdraw from social interactions to work on a project, get some rest or just take some time out. Some are positive, others negative, but all show that the brain is an interesting place — and that the fact that humans are social animals impacts us every day.
To wit: We often misuse the terms "extrovert" and "introvert." Introversion doesn't mean a dislike, necessarily, of social situations; it refers to the use of social energy. While extroverts feel energized by socializing, introverts feel depleted and require time out to recharge. Introversion can be paired with shyness or social anxiety, but that's a different category of issue related to how interactions happen and their potential consequences. If you need to spend a lot of time alone, you may notice that you start to react and feel different — and the reason lies in your neurology. Here's what happens in your brain when you spend a lot of time alone.
You're Better At Detecting Threats
This one makes perfect sense from an evolutionary perspective. A 2015 study found that people who spend a lot of time alone are very
good at detecting threats in their environment and are sensitive to potential signals that something's wrong. The reason? Humans have usually existed in family groups that protected each other from threats and worked together to defend themselves. If you're on your own, your brain switches to a more vigilant mode because nobody's around to watch your back in case, say, a wild animal is about to eat you. It's probably not a good idea to watch a lot of horror movies when you're spending time on your own, though, or you'll never stop looking over your shoulder.
Your Neurochemicals Can Shift
A new study shows that, in people who are chronically socially isolated, a neurochemical called tachykinin might mean they feel
more aggressive in general. Grumpiness and irritability, according to this study, aren't just because you've been away for a while and now find your friends irritating; they're a psychological change brought about by brain chemistry. Socially isolated flies and mice both showed increases in tachykinin that made them more aggressive and fearful of others, so don't be surprised if coming back into social life after some time away means you feel moodier and less tolerant than usual. It's just your neurons readjusting.
And Women Get The Brunt Of It
Fascinatingly, a study in 2016 found that the brains of people with different genders have
different reactions to social isolation, and that being a woman may mean a more intense response. The study looked at mice, and found that while male mice brains tended to react to isolation by chilling out, female mice brains found being alone a bit stressful and started producing a hormone called corticosterone, which is a reaction to really high-stress situations. We're not sure if this is replicated in humans, but if you appear to feel more stressed out by time alone than your male friends, it's possibly neurochemical in origin.
Your White Matter Changes
A 2012 study found that mice who are isolated for a long time
don't produce as much myelin, a crucial part of brain structure. Myelin is what makes up the protective "sheath" around your nerves, but you might know it as "white matter," as opposed to "gray matter," which comprises the nerve cells themselves. According to the study, a bit of social isolation dipped myelin levels, but didn't result in any different behavior, while spending a lot of time alone meant myelin levels dropped off quite a lot. Less myelin means your brain's signaling ability changes. This is probably why being alone for long periods actually changes our behavior — because our brains are communicating in different, possibly less effective ways.
You Find Happiness In Different Things
A study in 2009 was the first to actually look at MRI scans of self-described lonely peoples' brains, and found that a series of different "firing patterns" — neurological patterns of electrical activity in the brain — show up when you're lonely and
indicate that you're seeking happiness in ways that aren't social. Lonely people showed far less activity in their temporoparietal junction, a part of the brain that's linked to the perceptions of others, and researchers think that indicates that when you're happy as an isolated person, it's coming from something other than social interactions — like chilling in a bath or playing some awesome music on your own.
Your Brain Drives You To Crave Interaction
A set of studies in 2016 have shown that after periods of social isolation, your brain starts to kick in and
demand that you go and talk to somebody. The studies looked at dopamine, a chemical associated with positive feedback, in mice, and found that when they were alone, dopamine signals started to encourage them to seek out social contact, and rewarded them with a flood of happy feelings when they finally found some other mice to play with. This explains the craving for social interaction you may get after some time alone: It's your brain deciding that it's time you got outside, and giving you a massive hit of good feelings when you do.
There are a few seriously
positive benefits to time alone, but this one is top of the list: Harvard scientists discovered that when you form memories on your own, they tend to be stronger and longer-lasting than if you'd experienced the same thing with other people. Our brains, it seems, realize that we can't rely on others to remember vital information when we're experiencing them on our own, and so emphasize more accurate storage and recall. This is why studying on your own is often a good idea, and why you may remember those solo holidays much better than you do those group voyages in college (though there could be vodka-related reasons for that).
Overall, a bit of time alone isn't necessarily a bad idea. It gives us recharge time, and makes us appreciate our friends and family that bit more. But don't be surprised if longer-term isolation makes you feel like a different person — because, on several neurological levels, you really have changed.