Hi there,
I think it is quite common for them to drop their leaves when experiencing a change in atmosphere, although it can signal other issues as well. Are all the leaves falling off, or just the lower or upper ones? How much and what kind of light is it getting? Any change in watering habits? Can you post a pic of it so we might have a better idea what is going on? Look at me, you asked one question, and I fired a jillion back at ya!