WAS DRIVING 55MPH ON A DRY PAVEMENT. FELL ASLEEP AT WHEEL. LOST CONTROL OF VEHICLE. HIT A TREE. AT TIME OF IMPACT, NEITHER AIR BAG DEPLOYED. HIT HEAD ON SIDE DOOR WINDOW. VEHICLE HAD FLIPPED OVER. THE WINDOWS ALL CAME OUT. THE SEAT BELT RESTRAINED THE DRIVER. *AK