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. It’s common for people to experience at least one episode of sleep talking during their life, making it one of the most common abnormal behaviors that can occur during sleep. Research has helped clarify the symptoms and consequences of sleep talking, but there is much that remains unknown about the causes and treatment of this condition.

Source: Sleep Foundation