Source: Édouard Manet: Young Lady in 1866 (89.21.3) | Heilbrunn Timeline of Art History | The Metropolitan Museum of Art
Dressing gowns were originally worn by men starting in the 1770's. Banyans, a type of dressing gown worn by men in the eighteenth century, were inspired by Asian dress and frequently appeared in formal portraits. Women began to wear dressing gowns closer to the end of 18th century. Some forms of dressing gowns would have been worn only in the bedroom, but many were considered acceptable to wear in front of family and close friends. They were voluminous and were made of plain, white fabrics until the mid 1850's, at which point the silhouette became more fitted and colors and patterns were used. Women were not required to wear corsets with dressing gowns, although it is likely that some did.
Blue silk robe, 1870-1889, Accession no. 1979.019.001
Paisley dressing gown, 1870-1890, Accession no. 1979.074.001
By the late 1870's tea gowns became popular. Tea gowns were dresses that women wore when they received guests for afternoon tea, and were constructed from more substantial fabrics than dressing gowns, but were less structured than dresses women wore out in public. They were relatively formal because casual acquaintances might arrive for tea, so it was necessary to retain and image of propriety. Peignoir, a term that came into more common use at the turn of the 20th century, was also used in reference to a garment similar to a dressing gown. They initially were worn in the morning while completing one's dressing and grooming, but the term later evolved to mean any wrapper made of light fabric that was worn around the house or in the bedroom.
Peignoir, 1900, Accession no. 1986.045.015
Around 1900 a dress style known as the lingerie dress evolved. Lingerie dresses are reminiscent of undergarments, but unlike tea dresses, they were worn in public. Undergarments had become more and more elaborate, so that they became something to show off rather than something to hide, but, of course, it was not permissible to go out in one's actual undergarments. Thus, the appeal of lingerie gowns that hinted at what lay beneath while showing very little actual skin.
Detail of two piece lingerie dress, 1903-1904, Accession no. 1961.003.016a-b