When I first arrived for freshman orientation at American University, I was paired (albeit temporarily) with a stranger. She was from a state I had never visited—the mysterious land of Pennsylvania. She spoke of a substance I had never encountered—the native Pennsylvanians' storied "water ice." She pronounced it "wooder ice." She was my first roommate.

All of the Seventeen magazine articles and older kids warned me that there was a strong chance we would dislike each other. But I'm a clinger, and Kelly became one of my closest friends.

Not all of the college students who are moving into their freshman dorms this week will be so lucky. Some will reach their metaphorical hands into the roommate bingo-ball cage and draw a night-screamer, a day-masturbator, or worse. If the people around us influence our personalities and health, the people living five feet from our twin dorm bed do so all the more. Here are a few of the ways roommates can affect each other, according to research:

Anxious roommates make us more anxious, but happy roommates don't make us happier. In a 2012 study, University of Michigan health management professor Daniel Eisenberg found that as a randomly-assigned roommate became more anxious, the person living with them became more on-edge, too. Meanwhile, the roommates' relative levels of happiness had nothing to do with each other. Depression was transmitted fairly easily among men, but not among women. "Among women, by contrast, students with poor mental health appear, if anything, to do better when paired with roommates who also have poor mental health," Eisenberg wrote. This might be the only example ever of the narcissism of small differences being beneficial.

In a 2012 study, University of Michigan health management professor Daniel Eisenberg found that as a randomly-assigned roommate became more anxious, the person living with them became more on-edge, too. Meanwhile, the roommates' relative levels of happiness had nothing to do with each other. Depression was transmitted fairly easily among men, but not among women. "Among women, by contrast, students with poor mental health appear, if anything, to do better when paired with roommates who also have poor mental health," Eisenberg wrote. This might be the only example ever of the narcissism of small differences being beneficial. Your assigned roommate influences your drinking: This year, Eisenberg examined a cohort that had entered college in 2009 and found that living with a randomly assigned roommate who was a binge drinker greatly influenced the likelihood that a given college student would binge drink. The same trend did not hold true for smoking, drug use, gambling, or sex.

This year, Eisenberg examined a cohort that had entered college in 2009 and found that living with a randomly assigned roommate who was a binge drinker greatly influenced the likelihood that a given college student would binge drink. The same trend did not hold true for smoking, drug use, gambling, or sex. The roommates are also more likely to keep on drinking ... together: In 2001, the economist Bruce Sacerdote found that among Dartmouth freshmen, one roommate was far more likely to join a fraternity or sorority if the other did so, and 27 percent of roommate pairs joined the same Greek house. Living in a dorm with a bunch of students who drank beer before college also increased the likelihood that a given student would join a frat.

In 2001, the economist Bruce Sacerdote found that among Dartmouth freshmen, one roommate was far more likely to join a fraternity or sorority if the other did so, and 27 percent of roommate pairs joined the same Greek house. Living in a dorm with a bunch of students who drank beer before college also increased the likelihood that a given student would join a frat. Your roommate might influence your weight and dieting behaviors: In life, overweight spouses and friends tend to flock together, but this isn't true of college roommates. A recent University of Michigan study found that college women with heavier-than-average roommates gained less weight during their freshman year than those who were paired with thin women. Overweight women are more likely to diet and exercise, and the researchers suspected the thinner roommates picked up on these weight-loss behaviors. The obsession with body image can also go too far, however: One study that followed nearly 1,000 former college roommates over the course of 10 years found that the women who were bulimic in their 30s were more likely to have had college roommates who frequently dieted.

In life, overweight spouses and friends tend to flock together, but this isn't true of college roommates. A recent University of Michigan study found that college women with heavier-than-average roommates gained less weight during their freshman year than those who were paired with thin women. Overweight women are more likely to diet and exercise, and the researchers suspected the thinner roommates picked up on these weight-loss behaviors. The obsession with body image can also go too far, however: One study that followed nearly 1,000 former college roommates over the course of 10 years found that the women who were bulimic in their 30s were more likely to have had college roommates who frequently dieted. Roommates tend to rule or be ruled: A 2006 study of 102 pairs of female freshman undergraduates found that after four months of school, the roommates of women with dominant personalities began to behave more submissively, and vice-versa. The same study also found that women who exhibited warmth had similarly warm roommates, and the same was true for the women who were hostile.

A 2006 study of 102 pairs of female freshman undergraduates found that after four months of school, the roommates of women with dominant personalities began to behave more submissively, and vice-versa. The same study also found that women who exhibited warmth had similarly warm roommates, and the same was true for the women who were hostile. Eventually, they start to speak like one another: Researchers asked five pairs of male Columbia undergraduate roommates to say "She had your dark suit in greasy wash water all year" and "Don’t ask me to carry an oily rag like that" at four different times throughout their first semesters. (These sentences were chosen for complicated linguistic reasons.) By the time they came back from winter break, all of the roommate pairs were sounding a lot more like one another. The men who were better friends with their roommates exhibited even greater levels of this sort of linguistic "convergence." So if your goal is to develop a deep southern drawl, ask Housing Services if you can room with an Alabaman. And make sure you like the same beer—if she's a big drinker, you'll be guzzling plenty of it together.