From the New York Review of Books:
By my present stage of decline, I am thus effectively quadriplegic. With extraordinary effort I can move my right hand a little and can adduct my left arm some six inches across my chest. My legs, although they will lock when upright long enough to allow a nurse to transfer me from one chair to another, cannot bear my weight and only one of them has any autonomous movement left in it. Thus when legs or arms are set in a given position, there they remain until someone moves them for me. The same is true of my torso, with the result that backache from inertia and pressure is a chronic irritation. Having no use of my arms, I cannot scratch an itch, adjust my spectacles, remove food particles from my teeth, or anything else that—as a moment's reflection will confirm—we all do dozens of times a day. To say the least, I am utterly and completely dependent upon the kindness of strangers (and anyone else).
During the day I can at least request a scratch, an adjustment, a drink, or simply a gratuitous re-placement of my limbs—since enforced stillness for hours on end is not only physically uncomfortable but psychologically close to intolerable. It is not as though you lose the desire to stretch, to bend, to stand or lie or run or even exercise. But when the urge comes over you there is nothing—nothing—that you can do except seek some tiny substitute or else find a way to suppress the thought and the accompanying muscle memory.
But then comes the night.
More here.