In Guy de Maupassant's classic horror work The Horla, published in 1887, the French author writes with peculiar familiarity about a nightmare the protagonist experiences. The details form an accurate description of Sleep Paralysis and the 'Old Hag' scenario:
"I sleep--a long time--two or three hours perhaps--then a dream--no--a nightmare lays hold on me. I feel that I am in bed and asleep . . . I feel it and I know it . . . and I feel also that somebody is coming close to me, is looking at me, touching me, is getting on to my bed, is kneeling on my chest, is taking my neck between his hands and squeezing it with all his might in order to strangle me.
I struggle, bound by that terrible sense of powerlessness which paralyzes us in our dreams; I try not to cry out--but I cannot; I want to move--I cannot do so; I try, with the most viloent efforts and breathing hard, to turn over and throw off this being who is crushing and suffocating me--I cannot!"
In this short story, an entity--The Horla--comes from beyond this world like an incubus, a vampire in the night to suck the life force from hapless humans. In reading the tale, you can see how it has inspired other works that followed: vampiric elements and an epistolic style in Bram Stoker's Dracula (1897); and mind control from an otherworldly entity bent on domination can be found in both H. P. Lovecraft's Call of Cthulhu and in the classic science fiction tale The Puppet Masters by Robert Heinlein.
The detail involved in de Maupassant's description of Sleep Paralysis leads some scholars to believe he had first hand experience with the phenomenon. His deteriorating mental condition in real life also likely manifested itself as the main character's own struggle with sanity and the eventual contemplation of suicide.
If you've never read this short story, you should. It's a primer, a template for many stories that followed and should certainly be recognized for this.