Added to my list, sounds really suspenseful!
I was thinking more along the lines of *The Night Land* by William Hope Hodgson[1], though more specifically *Awake in the Night* by John C Wright[2, full text].
1. https://en.wikipedia.org/wiki/The_Night_Land
2. https://web.archive.org/web/20090524012412/http://www.thenightland.co.uk/nightawake.html