Whether you’re an introvert or an extrovert has a huge impact on how you do things, from networking to managing money. And as it turns out, your personality even changes how you react to that Starbucks espresso.

According to Brian Little, psychologist and author of Me, Myself, and Us: The Science of Personality and the Art of Well-Being, introverts actually become less efficient after drinking coffee.

“This deficit is magnified if the task they are engaging in is quantitative and if it is done under time pressure,” Little writes.

For extroverts, the opposite is true: After two cups of coffee, they’re actually likely more efficient. (We know, it’s not fair.)

The reason for this has to do with how alert introverts are to their environment as opposed to extroverts. According to certain theories and research on personality, introverts are already above this optimal level of alertness. “This suggests that performance will be compromised for introverts if they are exposed to stimulating situations, or if they ingest a stimulant (such as caffeine), which pushes them even further away from the optimal level,” Little explained to The Science of Us. A loud, crowded space would be similarly debilitating.

So if you identify as an introvert, you might want to reconsider your caffeine habit—or at least avoid drinking coffee right before starting a time-sensitive project or walking into that meeting. And if you’re a social butterfly, well, enjoy your latte, because it may just help you get ahead.