Why Do Introverts Love Being Alone? Here’s the Science

an introvert enjoys spending time alone

Chemically, there’s a good reason introverts really enjoy alone time.

As an introvert, I generally prefer books to parties and meaty conversation to light chitchat. It also means, by definition, I love spending time alone. When I suddenly find myself alone — like when my partner leaves for the night or a friend cancels plans — I feel giddy. Like, really giddy. For introverts, is there anything better than time to yourself?

And, like many introverts, when I don’t get that alone time, I feel stressed and drained. Every little annoyance is magnified, and I start snapping at the people around me without reason. Sometimes I feel anxious and depressed, or like I can’t even think or function, as my brain turns into a slow computer on dial-up. Yes, the introvert hangover is real.

So why do introverts love being alone so much? And why does socializing deplete us? Research has some interesting answers, and it begins with how our brains process reward. Let’s take a look.

The Introvert-Reward Connection

When writing my book, The Secret Lives of Introverts, I spoke with Colin DeYoung, a psychology professor at the University of Minnesota who had recently published a paper on introversion. He explained that one of the reasons introverts love alone time has to do with how we respond to rewards.

No, I’m not talking the gold stars your grade-school teacher slapped on your test when you did well. For adults, rewards are things like money, social status, social affiliation, and even sex and food. When you get promoted at work or convince an attractive stranger to give you his or her phone number, you’re earning a reward. Hurray!

Of course, introverts care about things like money, relationships, and food too. But researchers believe that introverts are wired to respond differently than extroverts to rewards. Compared to the more outgoing among us, we “quiet ones” are simply less motivated and energized by rewards. It’s like extroverts see big, juicy steaks everywhere, while to introverts, it’s mostly overcooked hamburgers.

In fact, as any introvert can tell you, sometimes those “rewards” aren’t just less tantalizing — they’re actually tiring and annoying. And that brings me to another slice of the science cake: how introverts react to stimulation.

Introverts Require Less Stimulation

Take, for example, two friends — one an extrovert, the other an introvert — at a house party. They’re crammed in a room with lots of people, and loud music blasts from huge speakers. Everyone is practically shouting to make their voice heard over the din. A dozen conversations are going on at once, along with a dozen things to pay attention to.

For the extrovert, this level of stimulation may be just right. He sees potential rewards everywhere — an attractive woman across the room, old relationships to be deepened, and new friends to be made. Most important, tonight is a chance to elevate his status within his group, that is, if he makes the right moves.

So, the extrovert feels energized and excited to be at the party. So motivated, in fact, that he stays late into the night. He’s worn out the next day and needs some time to recover (partying is hard work, after all), but to him, the energy spent was well worth it.

Now back to our introvert — see him hunkered in the corner? For him, this environment is simply too much. It’s too loud, there are too many things to pay attention to, and all the people in the room create a dizzying buzz of activity. Sure, he wants friends and to be liked too, but these “rewards” just don’t appear as tantalizing.

So, the introvert heads home early, where he watches a movie with his roommate. In his own apartment, with just one other person, the level of stimulation feels just right.

The Dopamine Difference

Chemically, there’s a good reason the introvert in the party scenario feels overwhelmed, and it has to do with a neurotransmitter called dopamine. Found in everyone’s brains, dopamine has been dubbed the “feel good” chemical because it helps control the brain’s pleasure and reward centers. It enables us to notice rewards, giving us energy to move toward them.

Another helpful thing dopamine does is reduce our “cost of effort.” Socializing expends energy, because we have to listen, talk, and pay attention to a stimulus. Technically, socializing is tiring for everyone, even extroverts. However, dopamine helps with that.

Extroverts have a more active dopamine reward system, according to DeYoung, and it’s built-in. As a result, they can better tolerate — and often overcome — the tiredness that inevitably accompanies socializing. Most of the time, they just don’t feel the same level of mental and physical fatigue.

Introverts Are Sensitive to Dopamine

Dr. Marti Olsen Laney, in her 2002 book, The Introvert Advantage, has a similar explanation. She writes, essentially, that introverts are more sensitive than extroverts to dopamine. As a result, introverts simply need less of it to feel its pleasant effects. Too much dopamine, and introverts get overstimulated. (Remember me snapping at everyone around me?)

Extroverts, on the other hand, may have a low sensitivity to dopamine, so they require more of it to be happy. Activity and excitement increase dopamine production, which explains why they enjoy socializing and “being on the go.”

Interestingly, Laney writes, introverts may prefer to use a slightly different brain pathway, one that is activated by acetylcholine, a neurotransmitter tied to long-term memory, perceptual learning, and the ability to stay calm and alert, among other things. Introverts may enjoy spending time alone in part because of acetylcholine; according to Laney, this chemical may produce a happy feeling for introverts when they’re quietly reflecting, concentrating, or turned inward.

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Extroverts Place More Significance on People

Finally, a study found that extroverts may simply find humans, well, more interesting and important. This makes sense if we think about introversion in terms of being less motivated to obtain social rewards.

In the study, the researchers looked at a group of different people and recorded the electrical activity in their brains using an EEG. As participants were shown pictures of both objects and people, the researchers evaluated their brains’ P300 activity. This activity happens when a person experiences a sudden change in their environment; it gets its name from the fact that the activity happens very quickly, within 300 milliseconds.

Interestingly, researchers found that the extroverts achieved the P300 response from viewing images of faces, while the introverts only had the P300 response after viewing objects. Essentially, extroverts’ brains became more active when looking at people.

No, this doesn’t mean that introverts outright hate people (although sure, the human race does get on my nerves from time to time). Researchers don’t fully understand introversion yet, but the study findings could mean that extroverts simply place more significance on people than introverts do.

As for me, you can find me at home tonight. Preferably with the house to myself, that is.

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Jenn Granneman is the founder of IntrovertDear.com and the author of The Secret Lives of Introverts: Inside Our Hidden World. Jenn is a contributor to Psychology Today, HuffPost, Susan Cain’s Quiet Revolution, Upworthy, The Mighty, The Muse, Motherly, and a number of other outlets. She has appeared on the BBC and in Buzzfeed and Glamour magazine. Jenn started Introvert, Dear because she wanted to write about what it was like being an introvert living in an extrovert's world. Now she's on a mission: to let introverts everywhere know it's okay to be who they are.