Nocturnal emission

A nocturnal emission, informally known as a wet dream, sex dream, nightfall or sleep orgasm, is a spontaneous orgasm during sleep that includes ejaculation for a male, or vaginal wetness or an orgasm (or both) for a female. Nocturnal emissions happen after stressful dreams in REM sleep which activate the sympathetic nervous system hence leading to ejaculation. Nocturnal emissions are most common during adolescence and early young adult years, but they may happen any time after puberty. It is possible for men to wake up during a wet dream or simply to sleep through it, but for women, some researchers have added the requirement that she should also awaken during the orgasm and perceive that the orgasm happened before it counts as a wet dream. Vaginal lubrication alone does not mean that the woman has had an orgasm. Due to the difficulty in collecting ejaculate produced during nocturnal emissions, relatively few studies have examined its composition. In the largest study, which included nocturnal emission samples from 10 men with idiopathic anejaculation, the semen concentration was equivalent to samples obtained from the same men by penile vibratory stimulation, although the proportions of sperm which were motile and which were of normal morphology were higher in the nocturnal emission specimens. In a detailed study, men and women reported that roughly 8% of their everyday dreams contain some form of sexual-related activity. 4% of sex dreams among both men and women resulted in orgasms. The frequency of nocturnal emissions is highly variable. Some reported that it is due to being sexually inactive for a period of 1–2 weeks, with no engagement in either intercourse or masturbation. Some males have experienced large numbers of nocturnal emissions as teenagers, while others have never experienced any. In the U.S., 83% of men experience nocturnal emissions at some time in their life. For males who have experienced nocturnal emissions, the mean frequency ranges from 0.36 times per week (about once every three weeks) for single 15-year-old males to 0.