In China's most modern and trendy city, Shanghai, the innocent but intimate pajama is at the center of a simmering public controversy that won't be put to bed.
The dispute revolves around wearing pajamas in public. On any given day on the commercial hub's crowded streets, locals in their nighties can be seen jostling for space with the latest mini-skirt fashion or the primly-pressed work suit and tie.
Daytime pajama wearers can be spotted anywhere in this city of 17 million, donning bedroom attire as naturally as a T-shirt on a hot summer day.
They cruise by on bicycles. They sip tea in quiet teahouses in the park. They saunter -- toothbrush and towel in hand -- through leafy lanes graced with the grand French concession homes of a bygone era to the public bathhouse.
In a recent survey on Shanghai's most fashionably unfashionable attire, 16 percent of respondents said they or family members often wear pajamas in public, and 25 percent sometimes did.
It was also considered one of the most irritating features of Shanghai city life along with domestic pets defecating in public, according to the study conducted by Shanghai Academy of Social Science sociologist Yang Xiong.
It is difficult to pinpoint just when pajamas became embroiled in one of Shanghai's fiercest etiquette wars in recent memory.
Many people deride the habit, which in China is peculiar to Shanghai, as uncivilized; smacking of an unforgivable lack of taste and poor pedigree in this class conscious city.
"People who wear the pajamas are degrading themselves because it shows their shallow taste and weak personal qualities," said Hu Shoujun, a sociologist at Shanghai's Fudan University.
"It's disrespectful to the others and, last but not least, it's not clean," Hu said.
But for resident Sun Mei, retired, wearing jammies is a perfectly acceptable comfort.
"Nobody has ever said to me it's inappropriate, and I don't feel it is either," Sun said as she pulled up to a local supermarket on her moped wearing a two-piece version decorated with cartoon figures.
Like many other residents she argued that she just wears them "around the neighborhood" -- a practical choice given most old homes in Shanghai have inadequate plumbing and locals often share public bathrooms.
There are other complexities surrounding the phenomenon.
One is the philosophical uncertainty in China's fashion circles over whether the pajama deserves its own place in the public wardrobe.
"If we were to take the pajamas as the pursuit of comfort, freedom and relaxation, it could be a trend," said Chen Hong, an editor with Elle magazine's Web site.
"But it's hard to say how one can wear pajamas in a fashionable way," Chen said.
Others point to the implied socio-economic message that wearing pajamas in public announces to others a certain life of leisure.
Another reason, according to Mou Lin, deputy fashion director with Elle magazine, is that pajamas are similar to the traditional Chinese suit of tunic and matching baggy trousers worn in ancient times.
But likely the main reason is the ongoing clash between people and the changing physical nature of Shanghainese society, said Yang, who conducted the survey.
A decade ago it was natural to wear pajamas in Shanghai's small lanes, where overcrowding meant forced communal living, but that has changed as more people have moved into the privacy of high-rise homes, he said.