So, it seems we may have a sleeptalker on our hands. Which should come as no surprise given the night terror history (frankly, talking in one's sleep is far more tolerable than screaming) and the fact that both aunts are known to chat away whilst sleeping.
During this afternoon's (lovely, lengthy) nap, I heard James say, "Truck, truck" as a truck drove past. A few minutes later I heard, "Hi. Hi. Hi." So I went in thinking he was up and ready to go for the afternoon.
Totally zonked out, eyes shut, sleeping.