Why do people wear pajamas? And why do they have such a funny name? Sit 'n Sleep investigates.

It's a nighttime tradition for many Americans to don their pajamas or PJs before heading to bed. Whether you're living in the Midwest during the winter and prefer wool PJs with the built-in footies or in sunny Southern California and wear short-sleeve PJs before going to bed, everyone has at least one pair. But, where did this tradition come from? Why do people wear pajamas? And why do they have such a funny name?

Traditionally, many Americans donned a long night shirt before going to bed up until the late 1880s. But, after English colonialists began to settle territories in the East and found that Indian loose-fitting jackets and trousers were quite comfortable and light weight, perfect for sleeping or lazing around the house, our bedtime attire began to change. In fact, the word "pyjama" traces its etymological origin to the Persian word "payjama," meaning "leg garment." In fact, the English began to wear them on those rare hot days in summer. But, it wasn't until the 1920s when the fashion fad hit the United States. Given the cold climate in much of America, designers began to add "footies" and make pajamas out of heavier, wool fabrics in order to keep Americans warm at night, expanding the popularity of pajamas.

Pajamas also became very popular with American children and are an iconic part of the American social milieu. Everyone remembers the famous Norman Rockwell painting of a child in PJs with the bottom flap open or Ralphie in "A Christmas Story" being forced to wear pink bunny pajamas on Christmas morning. The popularity of pajamas has reached the point where these days some people actually go out in public wearing them. It's not uncommon to see someone at the grocery store or walking their dog in slippers and PJs. PJs can also be used as workout gear because they're lightweight and perfect for activities such as Yoga.

So, next time you relax and get ready for bed, you'll realize that what you're wearing isn't just a comfy pair of lightweight pants and trousers but an American take on a traditional Eastern garment that's been around for centuries.