All normal for mine. It looses the leaves when you bring it inside. Are you in a warm climate or cold like mine? If you are overwintering it in a cold climate, keep it in an above freezing area. Let it die back and water only a small amount once or twice a month. Just enough to keep the roots from drying out, in the early spring move to a sunny spot and start feeding & watering more frequently. I warn you It will look like a dead thing for the winter....

Hey, I like the lights on the tree. Very cute. I know it's pretty normal for them to lose a lot of leaves when you bring them inside. I'm not sure where you are located, but you might try a humidifier in the room. I am in Colorado (zone 5 and very dry), so it helps some here.