NEW YORK » If there is any doubt that we’re living in the age of the individual, a look at the housing data confirms it. For millenniums, people have huddled together, in caves, in mud huts, in split-levels and Cape Cods. But these days, 1 in every 4 American households is occupied by someone living alone; in Manhattan, mythic land of the singleton, the number is nearly 1 in 2.

Lately, along with the compelling statistics, a stealth PR campaign seems to be taking place, as though living alone were a political candidate trying to burnish its image. Two notable examples: Eric Klinenberg, a sociology professor at New York University, recently published "Going Solo: The Extraordinary Rise and Surprising Appeal of Living Alone," a mash note to domestic solipsism, which he calls "an incredible social experiment" that reveals "the human species is developing new ways to live." And last fall, an Atlantic magazine cover story examined the rise of the single woman, a piece in which the author Kate Bolick fondly invoked the Barbizon Hotel and visited an Amsterdam apartment complex for women committed to living solo.

"I glamorized people who lived alone — I really wanted it for myself," said Bolick, who is in her late 30s and has her own apartment in Brooklyn Heights.

True, the benefits of living alone are many: freedom to come and go as you please; the space and solitude to recharge in a plugged-in world; kingly or queenly domain over the bed.

Still, as TV has taught us, the single-occupant home can be a breeding ground for eccentricities. Think of Claire Danes’ CIA employee in "Homeland," who turns her Georgetown one-bedroom into a control bunker for an ad hoc spying operation. Or Kramer on "Seinfeld," washing vegetables in the shower or deciding, on a whim, to ditch his furniture in favor of "levels."

In a sense, living alone represents the self let loose. In the absence of what Klinenberg calls "surveilling eyes," the solo dweller is free to indulge his or her odder habits — what is sometimes referred to as Secret Single Behavior. Feel like standing naked in your kitchen at 2 a.m., eating peanut butter from the jar? Who’s to know?

Amy Kennedy, 28, a schoolteacher who has a two-bedroom apartment in High Point, N.C., all to herself, calls it living without "social checks and balances."

The effects are noticeable, she said: "I’ve been living alone for six years, and I’ve gotten quirkier and quirkier."

Among her domestic oddities: running in place during TV commercials; speaking conversational French to herself while making breakfast (she listens to a language CD); singing Journey songs in the shower; and removing only the clothes she needs from her dryer, thus turning it into a makeshift dresser.

"The entire apartment is your room," Kennedy said, by way of explanation. "If I leave a bra on the kitchen table, I don’t think much about it."

In the experience of Bolick, who has also lived with roommates and boyfriends, living alone breeds "a very indulgent work style."

"I can work 24/7 for days on end, and I can let my whole apartment fall apart on me and not wash the dishes," she continued. "And nobody cares."

Bolick even has a home-alone outfit. "I have this pair of white flax bloomers that go down to my knee. They’re like pantaloons. They’re so weird," she said. "If someone comes over, I change out of them."

Even boyfriends have never seen her in them? "No, no," Bolick said, laughing. "That would be the height of intimacy if someone saw those."

What emerges over time, for those who live alone, is an at-home self that is markedly different — in ways big and small — from the self they present to the world. We all have private selves, of course, but people who live alone spend a good deal more time exploring them.

Rod Sherwood’s living-alone indulgences center on his sleep cycle. A music manager and record producer who works from his railroad apartment in Brooklyn, Sherwood, 40, said he’ll go to bed at 2 a.m. one night, and then retire later and later by increments, "until I go to bed when the sun comes up."

He mused: "I wondered how many times in a year I repeat that cycle? I’d be interested to chart it."

Ronni Bennett, who is 70 and writes a blog on aging, timegoesby.net, has lived alone for all but 10 or so years of her adult life. She said she has adopted a classic living-alone habit: "I never, ever close the bathroom door."

Leaving it open "is one of those little habits that makes no difference most of the time," she said. But when guests visit her two-bedroom apartment outside Portland, Ore., she added: "I have to make huge mental efforts to remind myself to close the door. Sometimes I think, Just put a Post-it note by the bathroom door. Well, wait, I don’t want them to see that."

Like many, Bennett also talks to herself — or, rather, to her cat.

"I’ll try things out on him when I’m writing," she said. "He’ll look at me like he’s actually listening. I wouldn’t discuss what I’m writing with my cat if someone were around."

Other people say their greatest eccentricities emerge in the kitchen. Eating can be a personal, even self-conscious act, and in the absence of a roommate or partner, unconventional approaches to food emerge. Drinking from the carton is only the start.

"I very rarely have what you would call ‘meals,"’ said Steve Zimmer, a computer programmer in his 40s who lives by himself in a Manhattan loft. Instead of adhering to regular meals or meal times, he said, he makes "six or seven" trips an hour to the refrigerator and subsists largely on cereal.

Bolick, the magazine writer, grazes on nuts and seeds, something that was pointed out to her recently when she shared a house with a married couple in Los Angeles. The husband told Bolick she would be fine in an earthquake because "I ate the equivalent of emergency rations."

Sasha Cagen, the founder of the website quirkyalone.net, is a kind of unofficial spokeswoman and lobbyist for singletons. Cagen, who has had roommates in the past but now lives alone, in Oakland, Calif., said that rather than cooking a big meal for one, an unappealing prospect, she fashions dinner out of "discrete objects": "I’m often, like, here’s a sweet potato," she said. "Let me throw this in the oven with aluminum foil and eat it."

It’s a solution to the problem that many face with food spoilage. But for Cagen, those makeshift dinners also underscore one of the pleasures of going solo. "There’s a freedom to really let loose and be yourself when you live alone that a lot of other people may envy," she said.

None more so than those who have never experienced it. Take Chad Griffith, 29, a Brooklyn-based photographer, who went straight from his parents’ house to living with roommates during and immediately after college to sharing an apartment with his fiancee.

"I haven’t lived alone a day in my life," Griffith said.

Instead, he observes what he calls "The Day of Chad," something he eagerly anticipates whenever his girlfriend goes out of town. "It consists of me doing the dumbest things possible," he said. "I would feel guilty if anyone else saw them."

What are some examples?

"I’ve been known to drink Champagne in the shower at 8 a.m.," Griffith said. "I’ll play ‘Madden NFL Football’ for 10 hours straight, eat a French bread pizza for every meal of the day."

But living alone is a skill that takes management, and Griffith has found he isn’t very good at it. The Days of Chad, he said, are about all he can handle.

"I literally have zero self-control," he said. "If I lived alone and didn’t have somebody to monitor me, I’d be a fat, out-of-work alcoholic."

For people who are comfortable and even good at living alone, there is often another concern: a fear that the concrete has set, so to speak, on their domestic habits and that it will be difficult to go back to living with someone else. "It’s definitely something that worries me," Kennedy said. "I can’t take the quirks back."

The longer she lives alone, she said, the less flexible she becomes — and the less considerate of others’ needs. "If I go on vacation with a group of friends, I feel a little overwhelmed," she said. "I’ve got to share this room with other people? We have to organize showers?"

Zimmer, the computer programmer, said he is also conscious of becoming too set in his ways, especially where sleeping is concerned. "I just do not sleep as well with someone else," he said. "A lot of homes have double master bedrooms. I can really see the value of that."

He added: "Looking back, maybe I should have had a roommate."

During a year he lived with a girlfriend, Sherwood, the music manager, said his nocturnal habits were hard to break. "I’d be up clicking on the computer until 4 or 5," he said.

But Bennett, whose last live-in relationship ended in 1976, said she doesn’t worry about being too quirky to cohabitate. "You know," she said, "I hear this stuff about ‘I just have too many bad habits.’ If I wanted to live with someone again, I think I could. You pull yourself back together."

That’s good news for Kennedy, who has developed the kind of quirky, absentminded habit that’s great if you’re an eccentric character in a Southern novel, but not if you want to be seen as good roommate (or romantic) material.

Pulling a sweater, boots and tights from her dryer-slash-dresser one recent morning, she forgot to grab her skirt, and left the house without wearing one. "I realized it when I got halfway to work — damn it, I forgot my skirt," she said. And it’s not the first time that’s happened.

When and if she lives with someone again, Kennedy said: "I think I’ll need to be with someone who has lived alone. We can commiserate and help each other resocialize."

MY ROOMMATE, MYSELF: ADVICE ON LIVING SOLO

With "Going Solo," Eric Klinenberg may have written the book on living alone, but he didn’t include a how-to guide. "There’s no road map," he said. "There’s not a lot of received wisdom for how to do it well."

Klinenberg was struck, for instance, by the number of young people who assumed living alone would be like college, where friends just drop by. "You have to learn how to organize your own social life, make plans, put yourself out there," he said.

We asked our solo dwellers what advice they’d impart to someone planning to make a happy home for one.

On the topic of solitude, the fundamental aspect of living alone, Rod Sherwood said, "Make sure you enjoy spending time by yourself and have work or a hobby that keeps you busy." He added: "And don’t worry when you start talking to yourself — at least someone is listening."

But since living alone and working at home can be "an intense combination," as Sasha Cagen put it, she recommended seeking out social contact by working at a cafe or a co-working space.

Another way to break up all that alone time is with houseguests, Kate Bolick said. Bolick suggested making your home "amenable to overnight guests, as one of the pleasures of living alone is being able to have friends stay with you for stretches."

To make your home a comfortable sanctuary, Bolick believes in bringing in nice things that you enjoy. "You need a throw blanket? Find the best, most pleasing throw blanket you can afford," she said. "You’re going to be spending a lot of time with it."

On a similar note, Ronni Bennett advised solo dwellers to "decorate as though you are a family."

"Get rid of the bricks and boards; buy real furniture," she added. "Just because you live alone doesn’t mean you shouldn’t have a pleasant, attractive place to come home to."

Bennett also passed along a cleaning tip that everyone who lives alone would be wise to follow. "Never let cleaning the bathroom slide," she said. "Even when the rest of the house is a mess, it feels cleaner when the bathroom is neat and shiny."

The challenge, she added, is to not let the house "get so awful you can’t face it."

Good advice, even for those who don’t live alone.