Pajamas are two-piece garment derived from the preceding garment, worn as (especially men's and boys') sleepwear, in Britain, the United States, and other countries. Pajamas in this sense consist of a jacket and trouser combination, made of a lightweight non-stretch material, similar to materials used in bed sheets, with the jacket closing down the front with buttons. These first appeared in Britain as a result of British colonial presence in South Asia in the 18th and 19th centuries, and by the early 20th century had replaced nightshirts as the dominant style of sleepwear for men and boys there.

A nighty (also called a nightdress) is a loosely hanging item of sexy nightwear. Its length may vary from hip-length, better known as "baby doll",  to floor-length (peignoir) but is typically knee-length. A nighty is manufactured from cotton, silk, satin, or nylon. It can be decorated with lace appliqués or embroidery around the cups and hem. Optionally, panties or thongs are worn under the nightgown. 

These are a sexy alternative to traditional pajamas.