Yes, I do use a bulb at night and I have since the day I got them. It is a white bulb for the day and a red one at night. I use a night bulb because the tank would get much too cold without one, especially during the winter. In the summer I do not use one. The light amount between day and night is enough that they still experience the cycle. At night, their light is the only one on in the room so it is still pretty dark. As I'm sure you can tell, the lights are a little different for everyone. From what Don said, you can see his wattage is much lower than mine. Part of that could be because my house is kept around 65*F. If you can test out your bulbs for a few days to see how your tank handles temperature/humidity before you get the frogs, that's best.