“Pajama Day” was once a novelty at school, the chance to be silly and wear attire usually reserved for the privacy of home. But these days many young people – 11-year-old Haley Small included – are wearing PJs in public, anytime and just about anywhere.

Haley’s favorite look: a T-shirt, flip-flops and pajama bottoms, with designs on them ranging from Snoopy to monkeys, basketballs to smiley faces.

“Part of it is because it’s cute; but the majority of it is because it’s comfortable,” says the sixth-grader, who lives in Glen Rock, N.J., and often wears her PJs, “so I can sleep the extra five minutes.” Pajama bottoms are better than jeans, she says, because they’re cool but less constricting.

Public pajama-wearing grew out of college students’ long-standing habit of rolling out of bed and into class. Now pajamas are a fashion statement, with such retailers as Old Navy, Target and J.C. Penney offering myriad styles for adults, teens and preteens.

The trend isn’t popular with everyone, though. School officials from Houston County, Ga., to Katy, Texas, to Southfield, Mich., to Bakersfield, Calif., have banned pajama-wearing at school.

And even some under-30s think it’s inappropriate to wear them anywhere but home.

“It isn’t a matter of being too casual,” says Olga Shmuklyer, a 28-year-old New Yorker who readily acknowledges to being a member of the “flip-flop” generation. She simply thinks pajamas aren’t flattering, for anyone. “They look like vagrants,” says Shmuklyer, whose own college-age sister wears pajamas in public, much to her “dismay.”

Others have noted adults getting in on the act. Preston Kirk says he was taken aback when one of the twentysomething cast members in his community theater group in Marble Falls, Texas, came to rehearsal in pajamas. “It took me an hour to figure it out,” Kirk, who’s 60, says of the woman’s outfit. “But then, I’m ‘old school.'”

Haley’s mom, Ellyn Small, says that the first time her daughter wanted to wear pajamas to school, “I was dead set against it.” Then she realized other kids were doing it and didn’t mind so much.

“The pajama bottoms and T-shirts cover just as much of her body, if not more than the clothes she would normally wear,” Small says. “I’m sure there will be plenty of times down the road for me to put my foot down and tell her she can’t do or wear something.”

Bob Hallman, another New Yorker whose 15-year-old sports sleepwear in public, says he’s also fine with it. “All I ask is that they wear PJs appropriately,” he says. “Not too big and too loose, not too small and too tight.”

Kristina Philips, a 20-year-old junior at Ashland University in Ohio, says she’ll wear pajamas to early classes, informal meetings or when she’s feeling too sick to wear regular clothes.

“But once you start wearing slippers with them, people start to make jokes about a pajama party,” she says, recalling how one student got teased for doing so her freshman year.

Haley, the 11-year-old in New Jersey, thinks they shouldn’t make such a big deal. She says that few people at her school, teachers included, have said anything about her pajamas. She does concede, however, that she may not be given so much slack, one day.

“It would depend on what type of job I had and what day it was,” she says. “If I had a press conference or something, I’d wear something nice. But I’m not a very dressed-up person myself. If you found me in a skirt, that would be amazing.”

For now, retailers say the demand for pajamas only seems to be growing.

Valerie Bent, who launched the Las Vegas-based Big Feet Pajama Co. a month ago, says she’s heard from many people who want to wear her company’s pajamas for outdoor activities – fishing, camping and snowboarding, among them. And some young people also have told her they plan to wear the one-piece, footed PJs to school.

“I’m a kid at heart. But I couldn’t even imagine wearing these out in public,” Bent says, laughing. “But I guess if you’re really brave …”