Antoinette Radcliffe admits it. She has her share of particularities.

The college freshman is a serious neatnik; she stays awake till the wee hours; and she makes no apologies for the alone time she craves.

"It was really important to me to have a single," the 18-year-old from Malvern says of her dorm-room choice. "I was worried about a messy roommate. I have a messy sister at home, and that's enough for now."

When Radcliffe applied for housing at the University of Pennsylvania, she pinned her hopes on a space to call her own, though she figured the chances were slim. After all, how often does a college newbie ever get a single?

Turns out, more often than anyone would think. What was once rare is now routine as more students arrive on campus with little interest in the traditional roommate experience, warts and all.

"The No. 1 desired space is indeed the single," says John Delate, executive director of residence life at Montclair State University in Montclair, N.J. Of 5,000 beds, 1,500 are in single rooms - and about 250 of those go to freshmen, he says. Of the approximately 1,600 freshmen who live on campus this year, about 15 percent have a private room and private bathroom - and no worries about someone else's hair in the sink. (It also costs about 20 percent more, Delate says.)

But even as college administrators accommodate freshman requests for singles, they worry about the effect on residential life and the transition from high school to higher ed. One research study argues that a first-year roommate can be a critical component to retention and college success.

"In residential colleges, making friends is a crucial step, and it's a crucial first step," says Daniel F. Chambliss, the Eugene M. Tobin Distinguished Professor of Sociology at Hamilton College in Clinton, N.Y. He coauthored the new book How College Works, based on following 100 students for eight years.

Having roommates, he says, makes forming initial friendships - and perhaps friends for life - that much easier. "The kids who were more socially connected, up to a certain point, did better academically," Chambliss says. "They're happier, more energized, and ready to get up in the morning and do things. Kids who were isolated get into a downward spiral."

In Radcliffe's case, she was delighted, and her parents were surprised, when she was assigned an 11-by-12-foot room - but no roommate - in Ware College House on the much-desired Quad at Penn.

"So far, I've been happy with my decision," says the biological-basis-of-behavior major. She allows that an instant friend might have made the first couple of days of orientation more enjoyable. But she also says it didn't take long to meet the woman across the hall, also in a single. "I say she's my honorary roommate."

At Penn, 582 other freshmen are staying in singles and 187 more have their own rooms in a suite, according to Residential Services. In fact, all freshmen who request a one-person accommodation usually get it.

Private rooms and baths - just like media lounges with flat-screen TVs, game rooms, and fully equipped kitchens - are part of the amenities race that started in the late 1990s. As demographics have shifted, resulting in a smaller pool of college students, many higher-ed institutions are competing through extras.

"That really matters," Delate says, noting that it can make or break a decision to attend. "One piece of that is the single room. People will ask about that immediately."

Solo accommodations from the get-go also reflect demographic shifts.

"The days of the five-person family . . . have lessened in our society," says Marty Redman, Penn's executive director of college houses and academic services. "Most of our students had their private retreat at home."

At the same time, first years often assume that a roommate is a fixture, as much a part of college life as extra-long sheets and late-night study sessions. At Penn, Redman notes, not all of the hundreds of singles are filled by request. In some cases, students are assigned when doubles run out - and, as proof you can't please all of the people all of the time, that has led to the concerned phone call. "They want to know, 'What's wrong with me?' "

Of course, Redman and other housing officials emphasize that the vast majority of freshmen live with someone else. For most, summer was spent deep into surveys and social media that serve as roomie matchmakers and enable students to get to know each other well before they meet in person. Many love the prospect of bunking with a buddy.

Not so much, though, for Penn sophomore David Glanzman. As a freshman, the computer engineering major from Wallingford weighed the pros and cons of solo living quarters.

"I understand how much having a roommate is part of the narrative of a college freshman," he says. "It's not something you give up lightly. But I've also lived in my own room my whole life. I enjoy having a little bit of privacy. I was nervous about giving that up for the first time in an environment where everything else is changing as well."

His to-himself space in Hill College House, he says, struck the right balance, especially because he hung out in the floor's common lounge. "I don't have any regrets," he says. This year, Glanzman, 20, joined three pals in a campus apartment, where he again has his own bedroom.

At Temple University's Morgan Hall, a $216 million dorm that opened last year, freshmen choose from various floor plans that include singles.

Dionysius Nugin-Waites, 18, paid extra to secure her own bedroom. She wanted a true single, but ended up in a five-person apartment that included a one-person bedroom. "I love it," she says. "This way nobody's touching my stuff." Nugin-Waites, a civil engineering major from Philadelphia, also had free rein to decorate, putting up a large mirror that takes up most of one wall. When she wants company, she walks out to four suitemates.

"Everybody is like, 'You're so lucky. I would love to have that,' " Nugin-Waites says.

Temple, however, intentionally limits the number of private beds, according to Kevin W. Williams, director of residential life. Echoing other housing officials, he says: "Our fundamental belief here is that our first-year students learn better, build better connections right away, are more engaged if they have to interact with people, vs. not interacting because they're in their own space."

In fact, Williams says he's not convinced freshmen should live in Morgan's apartment-style dwellings at all, even if they have a double. Instead, he sees value in the traditional dormitory, with roommates, that necessitates a walk down long corridors for the facilities and in the process offers chance encounters.

"We've given them everything they possibly need in there," he says of Morgan's apartments. "It's a different feeling. The hallways are quieter."

@exinkygal