Hi, Ed, @stephencbabcock. I've become aware of lights on/lights off curiosity. If I'm in a room and the lights are on, then no problem. Same thing of out-of-doors: if it's full daylight, again no problem. Strangely enough, if I get up in a dark––but familiar––room (as I do most mornings), once again I'm able to move about comfortably. (Dark, unfamiliar rooms? All bets are off!) I have the most difficulty with half-light: poorly lighted rooms and, if out-of-doors, pre-dawn and twilight. It's half-light that plays havoc with my balance. –Ray