Most people need no nighttime heat source at all for their Dragons...They are from the Australian Desert, which is #1) PITCH BLACK at night (another reason you cannot have ANY lights on at night, they don't sleep soundly at all, whether you think so or not), and then #2) The desert is very cool, even cold at nighttime, and they must be at a tank Air/Ambient temperature that is considerably cooler than their daytime temps are in order to both sleep soundly and for their bodies to be able to rest and recover...
You have to remember that they are Cold-Blooded creatures, not warm-blooded like us. Unfortunately a lot of people just insist on adding a nighttime heat source to their Dragon's tanks, and it's usually a Ceramic Heat Emitter (CHE), which is good in the sense that it doesn't emit any light, but the problem is that most homes are not kept below 60 degrees at night, and if they are we're talking like a few degrees below that...So they'll have a room temperature of say 55 degrees at an absolute lowest (that's pretty freezing for an inside room temperature), which means that the dragon's tank is about 58-60 degrees, and then they add a 50 watt or 100 watt CHE to bump their tank temperature 5-10 degrees!!! And then the tank ends up being over 80 degrees, which is HOTTER than their daytime temperatures...You see the issue...
You're Dragon is fine at night without any extra heat source if you room is 60 degrees.