Surge Protector -- strange reaction to light sources?

cf879

We have 2 power strips in our home in which the indicator lights both react to a light source in the following manner: during the day (in the presence of sunlight) the indicator lights shine red with a small flicker every now and then. In the dark, the indicator lights are off unless a light is shone on them, say from a flashlight etc. whereupon they light up red. When the flashlight or other light source is turned off or covered, they go off again. What in the world could cause the indicator lights to react in such a manner?