A nightie is thing worn by women to render themselves more attractive to their partner. Often the actual garment is so uncomfortable one could never actually sleep in it. It is more like wrapping paper (Wow, there is a real live woman under here! Just what I always wanted!) It is really intended to look good on the bedroom floor, or be hiked up during lovemaking. Unless it is really expensive it will probably be very scratchy and way too short. Often they are made a sheer fabric, with ribbons and frilly tufts as well as plunging necklines.