It is fashion history repeating itself, but this time, instead of jeans, it's the sweat shirt.

In the late 1970s, designers co-opted the jeans most people were wearing, rearranged the shape to fit those who were not so young and added fabrics and colors to provide a range of pants with a designer label at a cheaper price.

Since then, designers have taken workers' coveralls, army uniforms, classic polo shirts and even work shirts, refined the shape, color and fabric and called them their own.

The newest is the sweat shirt, favorite of sports enthusiasts and teen-agers who wear them for everything from running to studying to sleeping. Designers have added colors, some have added prints, others have gussied them up with piping and other contrast details. Such designers as Calvin Klein, Norma Kamali, Harriet Winter and Daniel Hechter were among the first to get into the act.

Now the original sweat shirt and sweat pants shape is simply one of several silhouettes showing up in sweat-shirt fabric. Others range from the blouson dress to wear to the office to padded-shoulder jackets and short "skimp" dresses that young people can wear with colored tights and flats.

The big appeal is the comfort of the cotton or cotton-blend fabric. And the clothes feel better the more you wear them. "Besides, when you get tired of wearing them outside, they are cozy and warm for sleeping," adds Harriet Winter.

Pictured from left:

Two-piece dress by Harriet Winter in brown sweat-shirt fabric, at Frankie Welch.

Sweat-shirt fabric used inside out for a striped top and pleated pants by Winks, at Saks Fifth Avenue. Bottoms are sweat-shirt gray, top is multicolor stripe on gray.

Norma Kamali shapes a black padded-shoulder zippered blouson in sweat-shirt fabric and pairs it with a black-and-off-white striped mini, at Bloomingdale's. (Shoulderpads are on Velcro and can be removed for easy washing.)

The sweat shirt extends to a skimp dress in off-white with broad red stripes by Savvy Sport at Woodward and Lothrop.