Nightgowns are nighttime apparel commonly worn by women. They are loose-fitting and usually made in the shape of a dress or gown.

Nightgowns, pajamas, nightshirts, and other types of night wear were unheard of up through the Middle Ages, when people usually just slept in the nude. The beginning of the textile industry brought long, heavy nightgowns and nightshirts. The original nightgowns, worn by both men and women, were shaped in the same way as a man's shirt, though longer, usually hanging down to the knees. In 17th century Europe, inspired by Asian influences, a type of dressing gown or banyan was popular with both men and women. Often made of silk, and fashioned after the Japanese kimono, banyans were used as nightgowns as well as casual lounge wear for the affluent.

Today, there are a plethora of nightgowns of all shapes, sizes, colors, and fabrics, usually worn by women. The nightgowns worn by men are primarily known as nightshirts today. Perhaps the first images in one's mind when considering nightgowns are silky, sheer teddy and baby doll type nightgowns and negligees, or floor length satin peignoirs, all of which are usually associated with newlyweds, honeymoons, and feeling sexy. These colorful and revealing nightgowns are created and worn to make a woman feel attractive and seductive; they are not normally designed for protection or warmth, but rather, for beauty.

"Baby doll" nightgowns, chemises, and negligees are usually sleeveless with thin straps or none at all, and the skirt part of the gown hangs down only to about the hips. Teddies are actually not nightgowns at all; rather, they are shaped more like a leotard or swimsuit. Floor length peignoirs are usually made of a sheer material, have spaghetti straps, and are close fitted. Yet each of these types of nightgowns is often used just on special occasions. For everyday use, it seems the most popular style of nightgown is the knee-length variety.

Depending on the type of fabric used, nightgowns vary almost as much as regular clothing. Cotton nightgowns are some of the most popular, with a large variety of cottons, from thin summer nightgowns with little or no sleeves to heavy flannel button-ups with long sleeves for cold, winter nights. Nightgowns can also be made of silk, satin, and nylon, to name a few. Most women find that they enjoy a variety of nightgowns. Their collection might include a lace or silky nightgown for feeling sexy, a flannel nightgown to take away the chill of winter, and a few comfortable cotton nightgowns for simply sleeping comfortably.