Nocturnal orgasms, or "wet dreams" are when men and women ejaculate or orgasm during sleep.[11] These occur during REM (rapid eye movement) phases of sleep,[2] which is the main stage when humans dream.[12] This implies that erotic dreams alone are enough to stimulate men, however erections accompany all REM phases.[1] According to self-report data, as many as 22% of young women may also experience orgasm during sleep, with such dreams being more common in college students in higher school years than younger students.[13] The orgasms experienced were positively correlated with high emotionality, including sexual excitement, but also anxiety.[13]