If he fell asleep, I don't think he would have called ATC in advance!!!
On climb out of Renmark, the pilot reported feeling hot and began to sweat. He checked that the cabin heat was selected off and the cabin air vents were open and climbed to 6,500 ft to allow cooler air into the aircraft.
The pilot reported that he lost consciousness in the climb with the aircraft auto-pilot engaged in heading mode and the elevator pitch setting trimmed for the climb attitude.