I do, but it is pretty high up above their head. it keeps the air around them a little warmer, still allows the ventilation to run up from the west side (which is lower than the east) and out. I do have a seedling mat hanging on the wall behind their roost, I think that helps keep the humidity down.
I used to think that the seedling mat did nothing, but one morning when it was pretty cold and I had not turned on the flat panel heater, they were all facing the wall for the slight heat. funny. The seedling mat is just barely warm, but keeps the wall behind them from getting cold.
Here is an old photo... If I remember I can try and get another later.
Yes, they are spoiled...