Sleep talking, known by the fancy scientific name of somniloquy, usually just amounts to a few random words or sounds spit out, rather than a full on sentence.
说梦话,有个花哨的科学性的名字叫梦呓,通常只是说出一些随机的单词或声音,而不是一句完整的句子。
Life Noggin
And by the same logic, sleep talking also occurs mostly during deeper stages of sleep.