Tony Judt movingly describes his experience of  Lou Gehrig's disease. By this point he is "effectively quadriplegic." Judt dreads going to bed:

Ask yourself how often you move in the night. I don't mean change location altogether (e.g., to go to the bathroom, though that too): merely how often you shift a hand, a foot; how frequently you scratch assorted body parts before dropping off; how unselfconsciously you alter position very slightly to find the most comfortable one. Imagine for a moment that you had been obliged instead to lie absolutely motionless on your backby no means the best sleeping position, but the only one I can toleratefor seven unbroken hours and constrained to come up with ways to render this Calvary tolerable not just for one night but for the rest of your life.

My solution has been to scroll through my life, my thoughts, my fantasies, my memories, mis-memories, and the like until I have chanced upon events, people, or narratives that I can employ to divert my mind from the body in which it is encased.