There is an old style 3way switch setup that can cause that effect?
I've got it in my house, 1930s setup.
When I had a new breaker box put in, my stairs lights were glowing at night, told the electrician the next day, and he said oh, the old style. He flipped the neutral and hot wires, and took care of it. He said those old type, makes a difference which side gets hot, but didnt elaborate.