Sleep talking is the utterance of speech or sounds during sleep without simultaneous subjective detailed awareness of the event. The utterances may be of annoyance to bed partners or other household members or even neighbors. Usually the sleep talking is brief, infrequent, and devoid of signs of emotional stress. However, it can consist of frequent, nightly, longer speeches, and include a content infused with anger and hostility.

Sleep talking may be spontaneous or induced by conversation with the sleeper. The disorder may be present for a few days only, or may last for several months or many years. Sleep talking associated with psychopathology or medical illness occurs more commonly in persons over 25 years of age. It can be precipitated by emotional stress, febrile illness, or sleep disorders such as sleep terrors, confusional arousals, obstructive sleep apnea syndrome, and REM sleep behavior disorder.