Flooded in darkness

From Mikhail Bulgalkov's description of a mental breakdown in The Master and Margerita:

It was twilight, in mid October. She went. I lay down on my sofa and fell asleep without putting on the light. I was awakened by the feeling that the octopus [1] was there. Fumbling in the dark I just managed to switch on the lamp. My watch showed two o'clock on the morning. When I had gone to bed I had been sickening; when I woke up I was an ill man. I had a sudden feeling that the autumn darkness was about to burst the window pains, flood into the room and I would drown in it as if it were ink.

[1] Another translation has this as a large squid