Some forms of sexual experience occur within a person’s mind, with or without sexual behavior. These are erotic dreams and fantasy—mental experiences that arise from our imagination or life experience or that are stimulated by the Internet, books, drawings, photographs, or movies.

Erotic Dreams

Erotic dreams, and occasionally orgasm, can occur during sleep without a person’s con­scious direction. One study found that 93% of men and 86% of women reported hav­ing erotic dreams (Schredl et al., 2004). A person might waken during such a dream and notice signs of sexual arousal: erection, vaginal lubrication, or pelvic movements. Orgasm can also occur during sleep; this is called nocturnal orgasm. When orgasm occurs, males usually notice the ejaculate—hence the term wet dream or nocturnal emis­sion. Women also experience orgasm during sleep, but female orgasm may be more difficult to determine because of the absence of visible evidence.