Sexsomnia, also known as sleep sex, is a type of parasomnia disorder. Parasomnia disorders are those that happen while you are asleep, and supposed to be "paralyzed" essentially. People with sexsomnia engage in sexual behaviors, like masturbation, sexual movements, sexual aggression or initiating sex while they are asleep. Their eyes may be open and they may be making noises, but they are unaware of their behavior once they wake up.
Sexsomnia can cause a lot of shame and distress for individuals with it, and any bed partners. Here is some more information about what it is and how it can be addressed.