I would be curious to see what "Pack" you got.. Your bearded dragon depending on size can be housed in a 10-20gallon sized tank/viv until they are generally around 9-15 months old then you would need nothing less than a 40 gallon breeder sized tank. 36x18x16 would be the rough dimensions for a 40gallon breeder tank. As for your question on lights, Yes you turn the lights off at night. Just like people animals don't sleep well with a bright light shining in their eyes! Dragons actually have whats called a "Parietal Eye" which helps them determine night from day. If any light is visible to this their third eye then they cannot sleep soundly.
So keep all lights off at night and you should be good, not even a "night bulb" or a colored bulb should be used at night as it still disturbs their sleeping habits. Your night time temps should not fall below 60* F in your dragons cage. So the use of your digital probe style thermometer (wal-mart for $10.00) will tell you if your temps are too low. IF infact your temps do get too low you should turn to the use of a Ceramic Heat Emitter The wattage you use will depend upon distance and the actual temperature inside the home. I use a 75watt in the winter just as a precaution mostly.
You shouldn't use a heat rock as these can overheat and burn the belly of your dragon resulting in death.
What
UVB bulb are you using and what are you using for a basking light?