Nightwear – also called sleepwear, nightclothes, or nightdress – is clothing designed to be worn while sleeping. The style of nightwear worn may vary with the seasons, with warmer styles being worn in colder conditions and vice versa. Some styles or materials are selected to be visually appealing or erotic in addition to their functional purposes.
Pajamas, often shortened to PJs, jimmies, jimjams or jammies, can refer to several related types of clothing. Pajamas are loose-fitting garments derived from the original garment and worn chiefly for sleeping, but sometimes also for lounging, also by both sexes. More generally, pajamas may refer to several garments, for both daywear and nightwear, derived from traditional pajamas and involving variations of style and material.
Pajamas are often worn with bare feet and sometimes without underwear. They are often worn for comfort by individuals in their living quarters. Since the late 20th century, some people in Britain and the US have worn pajamas in public, whether for convenience or as a fashion statement.