dead to the world

However, he slept right through the night, and was still dead to the world when I slipped out.

Simon hit him from behind on the back of his head. The size of his punch was enough to knock even the toughest senseless. Simon's victim fell to the deck. . . . There he lay, dead to the world.

[D]id you think that a being so sequestered as I am was already dead to the world, even while he was walking upon its surface?