At night you can turn all heating and lights off. These are desert reptiles so cope with very low temperatures; for beardies the cooling at night is actually quite important. It lets the beardies body rest properly.
The problem with your heating is that you don't have a thermostat - thermostats control the temperature by dimming or turning the heat source on and off (so you don't have to!). It's quite an essential piece of kit, especially if people aren't going to be around to turn lights off. With a basking bulb you should look at getting a dimming thermostat) have a look at Surrey Pet Supplies or Swell Reptiles - they are often the cheapest places.
What temperature are you turning the light off? And what thermometers do you use?