Why do some people talk during their sleep?

Imagine yourself tucked snugly under the covers in your bed, anticipating a blissfully restful night's sleep when all of a sudden, you're jolted awake by your partner! And as it turns out, they’ve done that because you were chattering away in your sleep, disturbing their peace and quiet. Now, being rudely awakened in the dead of night is bad enough, but adding the embarrassment of talking in your sleep just compounds the situation. After all, who knows what you've been …