A sleep bra is a piece of underclothing worn overnight to protect and support the breasts during sleep. These bras are generally made from soft fibers with smooth construction that makes them more comfortable to sleep in than a daytime bra. Also called leisure bras, sleep bras do not have underwires, the metal piece providing support at the base of many daytime bra cups, but they do often have molded fabric cups. Usually, the molded cups provide gentle support and are stretchy rather than firm. The cups generally do not have any padding or support panels.
Most of the time, this type of bra is worn to give a large-breasted woman comfort and support in addition to what is provided by her sleepwear. Sometimes, the bras can be worn by patients who have had recent surgery on the breast area. This type of bra, called a surgical sleep bra, provides support to the area that aids healing and is commonly worn after plastic surgery. Expectant or nursing mothers might also wear one to help them deal with the enlarged breast area that often comes with pregnancy. These bras can also be worn to cover the breasts for extra modesty in shared sleeping situations.
A sleep bra is usually made from cotton blended with an elastic synthetic fiber, like elastane, which is also known as spandex. This creates a fabric that has stretchy support but is soft to the touch. Some bras are made with synthetic fibers only, leaving out cotton in favor of soft microfiber nylon with spandex. Generally, it has wide straps on the shoulders, softly molding cups and a gentle band that provides smooth support without causing tightness or pinching.
The soft and flexible sleep bra bears many similarities to a light sports bra, but usually has softer fabric and lighter support. The shaped cups in a sleep bra help keep the breasts in place while lying down, which can provide a large-breasted woman comfort in more sleeping positions. These bras generally do not clasp in the back to avoid creating discomfort for back sleepers. Rather, the bra usually has a clasp in the front, between the cups, or no clasp at all. These bras are sized differently than daytime bras, often classified by general sizes such as small, medium and large rather than by a band and cup size.