Blanket Physics?

I woke up this morning scratching my head...
What in the world happened last night?
How was this possible?

So... I currently have a bed.
I have a mattress, with one of those 'fitted sheets' with a tiny bit of extra quilting. Then the usual "fitted sheet" that comes in every sheet set.
I have 2 pillows.
Then on the outer parts of the bed, I have a sheet, an afghan that my mom made for me a long time ago, and then a quilted comforter (not a big poofy one).
This morning I woke up to find...
My 'normal' fitted sheet had come unhooked from the top corner of my bed, and had slipped about a quarter of the distance in.
My top sheet, was completely shifted in the opposite direction, so that the corner of the sheet was approx where my neck was.
My middle layer of the afghan was also shifted to the left, and had also shifted down to about where my waist was.
My upper layer of the comforter was at the right height but shifted to the right so the corner was also about where my neck was.

What the heck?! Did I get in a fight last night while sleeping? Did those monsters that live under my bed do this just to confuse me?!
How is the physics of moving a middle afghan layer possible? Shouldn't the coverings all shift in the same way?!

I suspect I'll never know the answers to these questions... until the day I reach those pearly gates... that will probably be in my top ten questions to the Creator of the universe... to explain to me the physics of blankets.