I was concerned about the same thing! We had a huge temperature drop here too, and when Arizona experiences a temperature drop it can go from 80Fs to 30Fs overnight(26 to -1 C)! I noticed my toads were all dark in color and weren't as active. I kept the day/heat bulb on even through the night so they wouldn't get too cold. I did end up getting a heater. I bought a very small flat heater that is used for small sized aquariums. It is also located in an area of my tank that the toads can not get near it, as for babies, not really wanting any at this time, if they show up I will make the proper changes. The heater that I have does not go above 75F (23C). I have been monitoring the temperature gauge to make sure it isn't getting too hot for them also. Since I have added the heater my toads are much more mobile. They are hanging out in their plant, on the mossy deck, on their rock by their waterfall, etc. They are no longer huddled in a tiny corner together.