I think it was in The X-Files. After NDE (near death experience), a guy ended up in a macabre afterlife filled with hooded figures that, when they touched people, transformed them into their own likeness. I think he saw how they transformed a woman, and then they transformed him too, but he was saved. The man startes to sweat and slowly turns into one of those nightmares right there in the real world.
Thank you in advance.