Headlight problems on Corsica

We have a 1995 Corsica AT (140000 miles) that has developed a confusing problem with the headlights. The low beams only work in the daylight. The high beams work all the time but the low beams seemed to have gotten linked into some kind of light sensor even though we have done no work on the car. I say that it seems linked to a light sensor because in the afternoon when I pull into the garage I can see the lights shining on the wall. When I close the door I hear a click in the dash, the clock brightens and the low beams shut off.