Against the Grain by Joris-Karl Huysmans

These nightmares recurred again and again, till he was afraid to go to sleep. He would lie stretched on his bed, sometimes the victim of obstinate fits of insomnia and feverish restlessness, at others of abominable dreams only interrupted by the spasmodic awakening of a man losing foothold, pitching from top to bottom of a staircase, plunging into the depths of an abyss, without power to stop himself.

For several days, the exhausting nervous disturbance gained the upper hand again, showing itself more violent and more obstinate than ever, though under new forms.