Bayonet Bed

I went through a ten year phase where I was couldn't sleep on my tummy with my arms cradling the pillow.
I had this fear of knives, spring-loaded beneath the bed, shooting up through the mattress and my armpits, leaving me like an insect pinned in a display cabinet.
I have no idea where the fear came from, or even when I stopped worrying about it.
Last night it came back.

What could this portend?