Was the bed moving?

I turned on my back and looked up. Was I mad? drunk? dreaming? giddy
again? or was the top of the bed really moving down--sinking slowly,
regularly, silently, horribly, right down throughout the whole of its
length and breadth--right down upon me, as I lay underneath?

My blood seemed to stand still. A deadly paralysing coldness stole all
over me as I turned my head round on the pillow and determined to test
whether the bedtop was really moving or not, by keeping my eye on the
man in the picture.

The next look in that direction was enough. The dull, black, frowzy
outline of the valance above me was within an inch of being parallel
with his waist. I still looked breathlessly. And steadily and
slowly--very slowly--I saw the figure, and the line of frame below the
figure, vanish, as the valance moved down before it.

I am, constitutionally, anything but timid. I have been on more than one
occasion in peril of my life, and have not lost my self-possession for
an instant; but when the conviction first settled on my mind that the
bed-top was really moving, was steadily and continuously sinking down
upon me, I looked up shuddering, helpless, panic-stricken, beneath the
hideous machinery for murder, which was advancing closer and closer to
suffocate me where I lay.

I looked up, motionless, speechless, breathless. The candle, fully
spent, went out; but the moonlight still brightened the room. Down and
down, without pausing and without sounding, came the bedtop, and still