Sleep talking, formally known as Somniloquy, is a sleep disorder defined as talking during sleep without being aware of it. Sleep talking can involve complicated dialogues or monologues, complete gibberish or mumbling. The good news is that for most people it is a rare and short-lived occurrence. Anyone can experience sleep talking, but the condition is more common in males and children. Sleep-talkers are not typically aware of their behaviours or speech; therefore their voices and the type of language they use may sound different from their wakeful speech. Sleep talking may be spontaneous or induced by conversation with the sleeper.
Little is known about the content of the sleep talking: some talking makes no sense at all and some of it may relate to past events, experiences, and relationships that no longer have current relevance or emotional impact. Modern sleep science and the law accept that sleep talking is not a product of a conscious or rational mind and is therefore usually inadmissible in court.
Although not physically harmful, sleep talking can cause embarrassment and can annoy a bed partner, roommate, or be disruptive in group-sleeping situations. Because of this, sleep talkers are sometimes afraid to sleep away from home and can cause insomnia in a person sleeping nearby.
Sleep talking may be brought on by stress, depression, fever, sleep deprivation, day-time drowsiness, alcohol, and fever. In many instances sleep talking runs in families, although external factors seem to stimulate the behaviour. Sleep talking often occurs concurrently with other sleep disorders such as nightmares, confusional arousals, sleep apnea, and REM sleep behaviour disorder. In rare cases, adult-onset frequent sleep-talking is associated with a psychiatric disorder or nocturnal seizures. Sleep talking associated with mental or medical illness occurs more commonly in persons over 25 years of age.