I thought of this, but I wasn't sure if it was 1) one of those 'wait, that plot point really means...' things that is unintentional or 2) one of those 'wait, that plot point really means...' things which is
deliberate. Either way, a (n ignored) component of Max's psyche has given up on life and wants both itself and Max dead, and there's not really much of a way of un-darking that once you think of it. See also:
Fridge Horror.
Not going to argue for a second that this was any of the writers's intentions... but at least having a part of his brain desperately longing for the sweet oblivion of death explains Max's night terrors.
...Other totally meaningless, stupid thoughts: If the Narrator is Max's Superego and Max himself is the Ego, does Max's Id normally hang around in Max's brain and watch TV or harrass the Narrator or write horrible fanfiction about Flint Paper or whatever? What does he manifest as?