© Shutterstock

Nighttime ritual -

For many, their nighttime ritual includes pulling on a pair of pajamas. But when did we start wearing pajamas, and why?

© Getty Images

Origins of the pajama -

Pajamas are soft, loose sleepwear derived from the free-flowing Indian garment tied at the waist with drawstring known as the dhoti.

© Getty Images

A word about pajamas -

According to the Oxford English Dictionary, the word pajama is a borrowing via Urdu from the Persian language.

© Getty Images

Etymology -

The Persian pāy-jāma comes from pāy, pā (foot or leg) and jāma (clothing).

© Public Domain

Early references -

One of the earliest known references to pajamas in the West dates back to the early 17th century when French travel writer Jean de Thévenot mentioned the Portuguese wore them when going to bed in one of his travelogues.

© Getty Images

"Pajama" enters the English language -

The word pajama, and the garment, was incorporated into the English language via Bengali, during the Raj (the period of rule of the British Crown on the Indian subcontinent).

© Getty Images

Pajamas as a uniform -

In India, pajamas were recorded as the "uniform" of both the Indian gentry and peasants. The garment also transcended sex, being worn by both men and women.

© Getty Images

"Mogul's breeches" -

When the colonial British brought pajamas to England in the 18th century, merchants called them "mogul's breeches."

© Getty Images

Victorian nightgown -

Sleepwear in the Victorian era looked more like a dressing gown or robe. And there was a reason for this. Sleepwear designed this way kept dirt and grime away from everyday clothes and off the bed sheets.

© Getty Images

Loungewear for men -

Increasingly in the 19th century, pajamas were regarded as comfortable fashionwear. By the 1870s, the garment had become popular loungewear, mostly for men.

© Getty Images

Luxurious accessory -

By the early 1900s, pajamas were a practical but still rather luxurious nighttime accessory.

© Getty Images

Liberation -

The liberation of the pajama took place more or less the same time as the "liberation" of women.

© Getty Images

Fashion statement -

Throughout the 1920s and '30s, women in the Western world wore pajamas essentially as a fashion statement.

© Getty Images

A new wave in sleepwear -

Spearheading this new wave in sleepwear was French fashion designer Coco Chanel (pictured), who was often photographed in pajamas,  accessorized with her signature pearls.

© Getty Images

Changing gear -

And it was during the 1920s and '30s that pajamas became a sought-after garment by women from all walks of life, but especially those of high society. Here, a pajama set for women drivers is being modeled.

© Getty Images

Style and glamour -

Pajama design mirrored that of the "flapper" style—loose-fitting silk garments with elaborate embroidery and beading. These glamorous pajamas were often worn as evening wear, paired with high heels and expensive accessories.

© Getty Images

Star attraction -

The star attraction of the pajama was not lost on Hollywood. Some of the era's most famous actresses were seen wearing luxury loungewear, including Ginger Rogers (seen here modeling a house dress made up of a large pair of satin pajama pants and a satin train).

© Getty Images

Model looks -

Here, movie star Katharine Hepburn models a gold robe and pajamas set. Endorsements by Hollywood's most beautiful and alluring did wonders for pajama sales.

© Getty Images

In with the new, out with the old -

And pajama style was in marked contrast to the traditional old-fashioned long johns still favored by many men. In this image, legendary comedy duo Stan Laurel and Oliver Hardy strike a contrasting pose.

© Getty Images

A stylish way to end the day -

By the 1940s, pajamas made for men were being worn more frequently, perhaps because it simply made sense to enjoy a good night's sleep wrapped in warm, comfortable apparel. Wearing pajamas also provided a stylish and practical way to end the day.

© Getty Images

'The Pajama Game' (1957) -

'The Pajama Game' further promoted the pajama's appeal in the 1950s. Set in a pajama manufacturing facility in Iowa, the film stars Doris Day, who appears on the movie poster wearing a heart-patterned pajama top.

© Getty Images

Freedom of choice -

And that's when women started wearing baggy pajama tops designed for men, as a way of expressing a burgeoning sense of sexual freedom as the 1960s dawned.

© Getty Images

Blurring the lines -

In the sexually permissive '60s, lingerie began to blur the lines between traditional sleepwear and more risqué nightwear.

© Getty Images

Baby doll -

The advent of the "baby doll" look suddenly made wearing pajamas a very sexy proposition.

© Getty Images

Flirty and frilly -

Again, Hollywood wasted no time promoting the frilly and flirty look. Pictured is Barbra Streisand in a baby doll dress as Fanny Brice's most famous creation "Baby Snooks" on the set of Columbia's 'Funny Girl.' Released in 1968, the movie marked Streisand's film debut reprising her Broadway role.

© Getty Images

Pajamas and bed-ins -

A year later, John Lennon and Yoko Ono made the humble pajama look cool during their famous bed-ins for peace in Amsterdam and Montreal.

© Getty Images

A new dawn -

The seductive bedtime "nightie" look was carried over into the 1970s. But the pajama was about to get a dressing down.

© Getty Images

Unisex pajamas -

In the 1980s and '90s, a more baggy informal style of pajama, the kind traditionally favored by men, was increasingly the sleepwear of choice for women. The unisex look had arrived!

© Shutterstock

The baggy flannel look -

Opting for comfort over style, many women began adopting loose-fitting flannels topped with a T-shirt as their preferred nightwear.

© Shutterstock

Wear it well -

And while sleepwear continues to change and break convention, at the end of the day it's all about being comfortable and what you feel good in.

Sources: (Cozy Earth) (Hernest Project) (Fashion Capital) (The Fashionisto)

See also: What your sleep pattern says about your personality

© Shutterstock