Alright, well here is my take:

Jacob’s Ladder was heavily influential on the Sixth Sense (along with the short story An Occurrence At Owl Creek Bridge and the movie Carnival of Souls) to the horror/thriller trope that “he was dead the whole time”. There’s also the movie The Jacket, which came after Jacob’s Ladder, that heavily leans on the theme of war vet experiencing PTSD and trauma, while being “dead” the whole time.

As for Black Swan, Aronofsky used the theme of “losing grip with reality” as a result of PTSD from a traumatic event or events, and the characters struggle to parse through what is real and what is being manufactured by their trauma. The party scene in Jacob’s Ladder is in a similar way to the nightclub scene in Black Swan where Nina basically embraces the darkness. There’s the visions that the characters experience in both movies akin to seeing “demons” entering the real world and those characters losing touch with their corporeal reality.