SHANGHAI, China -- Zhan Chunyong likes nothing better after work than to slip into her pajamas and head out to do grocery shopping.

On a recent afternoon, the 42-year-old security guard strolled through a crowded street market in central Shanghai wearing neatly pressed white pajamas with blue pinstripes.

Other shoppers wearing pajamas or nightgowns haggled with fishmongers or looked over the goods at the stalls of vegetable peddlers.

It's a common sight in China's biggest, most prosperous city: men and women in public dressed as if in the intimacy of their bedrooms.

You can see them in their nightclothes on busy sidewalks, walking amid the business suits as if it were the most natural thing in the world.

At supermarkets, they shuffle in slippers behind shopping carts. Some zip by on motor scooters, plaid flannels flapping in the wind.

Shanghainese say they've been wearing pajamas in public for at least 10 years, since the economy took off and they could afford to add sleep wear to wardrobes that consisted of little more than drab gray and blue Mao suits.

Far from being embarrassed, they say pajamas are more comfortable than regular clothes -- especially in Shanghai's notoriously hot, sticky summers. They're a luxury and a way to flaunt new wealth.

"Only people in cities can afford clothes like this. In farming villages, they still have to wear old work clothes to bed," Zhan said.

Residents seem to look on it as a charming quirk. So do officials in charge of keeping Shanghai looking smart.

"Some say it's not civilized, but it's just a harmless habit of the residents," said Zhang Limin, a spokesman for the City Environment Supervision Office.