After a protracted and quite robust day of concert rehearsal, my weary limbs sought comfort under a tender blanket and, with my head cocooned in pillows, I contemplated the notes and bars that needed more practice before drifting off to sleep.  Why does such sublime rest, when well-earned, always seem more heavenly than at other times? Perhaps because precious time has been stolen from the day.    Waking up after a luxurious nap is always so difficult, with much wallowing and drifting in and out of dreams as the mind resists the urge to awaken..