For me, this is really the big one. We know they’ve been back in SB for several days (minimum) and he’s never once noticed that he doesn’t need sleep? And that’s he not getting tired?
If I was on the writing team, I’d put it this way:
It looks to me as if people with unresolved issues are more vulnerable to dark influence. The dark spirit strengthens their fears and hatreds, making sleep impossible — which in turn changes their personalities and behaviours — but it also sustains their bodies through what would otherwise be terminal sleep deprivation. Hook has dealt with his issues, so he sleeps soundly and doesn’t show signs of dark influence.