[That works for Yato - it's a nice, comfortable thing they've got going between them; no need to shake it up with sappiness or their (his) issues. So long as Katsuki knows he's not a total hopeless idiot and trusts him enough to rely on him, all is well in Yato's book.]

Eh? Oh-- No, no way...! Uh, er, it is late, isn't it? I should probably let you sleep, huh? Um, have a good night and sleep well...? Hehe...

[At least as well as he can given SOME IDIOT woke him up to chat in the middle of the night.]