It happened to me and I think it will still be happening to me.
The main reason why my Grandiose delusion gets worse at night was (and is) because no strangers around me at home to “disapprove of” my delusional thinking. Auditory voice might have also added fuel to the fire by “confirming” my identity in delusion of grandeur.
Even when I’m doing fairly well, it’s at night that my thoughts get more intense and start to get more extreme.
Like when me and my GF argue sometimes, I can get really freaked out at night and overthink my responses to where it’s just massive overkill.
My voices and hallucinations are really bad at night. When I don’t get enough sleep, I go back to bed and take many naps. My motivation is like a zero.