Hello Delilaheve! Welcome to the forum.
To answer your question, a 12-12 lights on light off cycle is better for your beardie. They need time to sleep, just like you and me.
To go further, you can actually allow the terrarium to cool substantially during the night.
During the day time, you want a basking spot (an area large enough for your dragons entire torso to get into) that is about 100 degrees F or 38 degrees C (this is somewhat debated, some people I have seen have healthy dragons with a basking spot as cool as 90 degrees F or as hot as 110, which is a range of 32-43 degrees C). During the day, the ambient temperature (the temperature of the tank on the cool side) should be about 80 degrees F, or 27 C, though a few degrees one side or the other is again fine. I wouldn't go lower than 75F or higher than 85F, personally.
During the night time, the temperature of your house should be perfectly fine without any other heat source, assuming that's above 65 degrees F (18 C). Ideally, 70-80 degrees F (21-27 C) is the perfect temperature for your bearded dragon overnight, but they can tolerate a temperature as low as 55 degrees F if they have to - though long term this may cause some health issues.
Hope that helps!