Sleep sex disease, or sexsomnia, is a non-rapid eye movement (NREM) parasomnia manifesting with making sexual voices, talking/yelling, masturbation, caressing another person, sexual intercourse, or agitated/ aggressive sexual actions during the sleep. During the N3 period of NREM sleep these manifestations are observed: seeing sexual dreams, frequently experiencing erection-ejeculation in the sleep, masturbation, starting the sexual activity with abnormally increased desire without caring about desire of the partner during sleep, staring vacantly and absently, exhibiting actions and fantasies during the intercourse that are very different from those of normal, caressing, screaming, groaning, making orgasm voices, coitus with or without orgasm, cursing, physical or emotional violence against their partner, and insulting the partner. The facts that its diagnostic criteria are currently not known well, the physicians other than sleep medicine experts don't query the signs of the condition, and the patients and/or partners don't want to share what they experience because of the sexual nature of the manifestations make detecting the true frequency of this disease very difficult. Enhancing awareness of this parasomnia which also has medicolegal aspects will make the diagnosis and treatment easier.