Ejaculation during sleep for a male, or lubrication of the vagina for a female. In 1953, Alfred Kinsey found that nearly 40% of the 5,628 women he interviewed experienced at least one nocturnal orgasm or "wet dream," by the time they were forty-five years old. A smaller study published in the Journal of Sex Research in 1986 found that 85% of the women who had experienced nocturnal orgasms had done so by the age of twenty-one or earlier. Women who have orgasms during sleep usually have them several times a year. Dr. Kinsey and his colleagues defined female nocturnal orgasm as sexual arousal during sleep that awakens one to perceive the experience of orgasm. Similar studies find that a much higher percentage of boys and men experience wet dreams.
Relatively small studies conducted in the 50s found that nocturnal orgasm was reported by about 40% of women with the diagnosis of a neurosis or psychosis, and as opposed to only 6-8% of control women. Studies conducted in the 80s found that the incidence of nocturnal orgasms in healthy women is much higher and is associated with positive attitude to sex, knowledge about nocturnal orgasms and sexual liberalism. Later studies concluded that it was more about “erotic responsiveness" than other factors.