A nocturnal emission, also called a wet dream, is an involuntary ejaculation of semen (sukka) during sleep. The cause of these experiences is uncertain but popular wisdom puts them down to either erotic dreams or the build up of semen in the prostate. Many religions hold that nocturnal emissions rob a male of his virility or are polluting. The   Manusmuçti says: `A  Brahmin student of the Vedas who has had a night emission should bathe, worship the sun, and chant three times the Vedic verse that begins ßLet my virility return to me againû.' According to the Bible, a nocturnal emission renders a man impure and that this can only be remedied by ritual washing (Leviticus 15, 16-17). The Vinaya, the Buddhist monastic rules, says that masturbation is an offence, but having a nocturnal emission is not. The Buddha mentioned that nocturnal emissions occur as `a result of a dream' (supinantena, Vin.I,294). He also said that if a monk falls to sleep carefully and mindfully he is less likely to have one.

During the Third Council some participants maintained that an enlightened male, an arahat, could have a nocturnal emission and that these experiences were caused by malevolent gods. Both ideas were contradicted by the orthodox monks (Kv.163). See   Sexual Behaviour.