Crib talk

Crib talk or crib speech is pre-sleep monologue made by young children while in bed. This starts somewhere around one-and-a-half years and usually ends by about two-and-a-half years of age, though children can continue longer.[1][2] It consists of conversational discourse with turn-taking often containing semantically and syntactically coherent question-answer sequences. It may contain word play and bits of song and nursery rhyme.

Crib talk has been found in deaf children in their early sign language.[3] It also occurs in autistic children.[4]