I stumbled on this site pretty recently and have been chewing my 62-year-old mom's ear off about it. Which, to my delight, prompted her to offer up her own trauma for identification.
She thinks she was about 11 (which would have made it 1958 or so) and living in New Jersey. She saw an episode of what might have been a weekly T.V. program depicting eerie stories. (I just combed the episode guides of THE TWILIGHT ZONE and ALFRED HITCHCOCK PRESENTS and viewed every title that seemed a possibility, even straying into the early sixties to be thorough.)
In the damaging episode, a beautiful young girl receives instructions to climb a spiral staircase to the top of a castle turret (?). She does so carrying some sort of light source (lantern? candle?) and reaches the top to find a room with a mirror.
Peering into the glass, she glimpses herself as a withered old woman (possibly just old, but also possibly torn up- or debauched-looking in some way.)
Y'know, it may have been my mom who actually saw this, but the act of describing it has planted such vivid imagery in my own mind that I'm as eager as she is to have the thing named!