Some nights when I go to bed, when the street has gone qu...

Some nights when I go to bed, when the street has gone quiet and my brain starts to relax, I hear a sound. Beneath the thrum of insects. Hiding behind the meaty grumbling and pumping of my own organs, there is the trickling of water.
I'm not sure if it's real.
But it makes me nervous.
I lie there trying to calculate the size of the cavern being created by this stream of water, the persistent tinkling at the edge of my hearing.

I imagine parts of the wall and ceiling of the cavern regularly peeling off and falling to be slowly dissolved by the running water. The vacuole grows until, inevitably it has undermined my home. A great, invisible bubble lurking beneath me. Ready to swallow me whole.

A limestone cavern with an icy river to drown in. Long trapped gasses not meant for breathing. Pillars of rock. Beautiful, tall and sharp, far below. If I'm not skewered, perhaps the fall will kill me. As the bedroom tilts towards the gaping hole, a beam might dislodge from the roof of my house and dash out my brains.

Of the multifarious dreams of my own demise, the 'hole in the ground' is a particularly disturbing and all-too-common meme; a ring of crumbling brown walls. Hand holds that melt under desperately grasping hands. Falling. Falling in towards that dark, cold spot; the Dead Centre.
In nightmares, there are oily horrors that breed in that pitch. Dumb, hungry abominations that smother their victims slowly, sitting on their chest, filling their ears, their eyes and their mouths with wet soil. It might take days to expire; immobilised, heart thumping and lungs straining and no light to glint off their translucent teeth...

Perhaps it's all in my head.