Nights On the Edge

Bess, Ralph, Celeste, and I have our assigned places on the bed at lights out.  After a ritual back rub, Bessie Anne moves over to her pillow.  After racing around and working off a last burst of energy, the cats lie down at the foot.  I, however, am the only one who plays by the rules.  The other night I awoke any number of times, clinging to the edge and in danger of falling off.  Bending a knee sent it into space, out from under the blanket and into the cold.  Bess had shifted to my pillow and the cats were on my feet.  Some arcane law of physics causes dog and cats to become as heavy as marble after I fall asleep.  Like the migrating rocks of the desert, these lumps crowd closer and closer until there's no room for me.  I can't turn over and I can't move the critters.  Cleverly, last night I devised a plan to thwart a repeat performance.  Instead of my customary place, I lay down toward the middle of the bed, leaving plenty of leeway to the edge.  Did I sleep the night through?  I did not.  I kept waking up to see if the plan was working.