Is nightfall normal according to Islam?

Answer 1

Muslim scholars consider ejaculation something that makes one temporarily ritually impure known as Najis; it means that a Muslim who has had an orgasm or ejaculated must have a Ghusl(which means: full ablution) before they can touch the Qur'an or perform the formal prayer known as salat. Informal supplications and prayers known as du'a do not require a bath.

A wet dream is not a sin in Islam. Moreover, whereas a person fasting (in Ramadan or otherwise) would normally be considered to have broken his or her fast by ejaculating on purpose (during either masturbation or intercourse), nocturnal emission is not such a cause. He or she is still required to bathe prior to undergoing some rituals in the religion.

Source: Wikipedia.