One of my 2 geckos looks lethargic and last night, I found it laying upside down. I righted it and it was basically limp. It has moved a bit today. The setup is a 20 gallon tank, 1 side has a hide with a heating pad underneath. The other side (cool side) of the tank has a hide with Sphagnum moss inside. I've had the 2 geckos for about 5 years. Since I introduced the cool side hide about 2 years ago, the larger, healthier looking gecko spends most of its time there. Also, I introduced a heating lamp (on medium power) about a month ago since our house is on the colder side in winter. The lamp sits on top of the mesh cover in the middle of the tank. Hopefully the heat didn't hurt the gecko as I read overheating could be the cause? Any suggestions. Since there are 2 geckos it's hard to figure out if the sick one is eating and pooping normally. Any help would be appreciated.