Beardies require a temperature gradient in their enclosures because they can't regulate their body temperatures like. They have to thermo regulate, which means that they have to move between areas of differing temperatures in order to regulate their internal temperature. To produce heat and a basking spot in your enclosure, you can use either a ceramic heat emitter, a reptile basking light (red, blue or white) or just a plain old household light bulb.
The best fixture for any of these choices is a porcelain dome light fixture. This type of fixture is a must with a ceramic heat emitter due to the amount of heat they produce. The temperature for this basking spot you created should be around 110oF for juveniles and can be around 95oF for adults.
Your Beardie will also need an area to cool down if he gets too warm. At the opposite end of the tank, you should try to keep the temp around 75-85oF. A few degrees within this temperature are just fine. Night time temps shouldn't be allowed to drop below 60oF, whereas 70-75oF is more comfortable for them. Don't guess on temps - you could cook or freeze your Beardie! Use a good thermometer, one on the cool side and another near the basking site.
A thermometer on the hot part and another on the cool part of the enclosure will make sure that your temps are in the range they should be in. Do not use hot rocks as they are potentially dangerous! Dragons don’t sense heat well with their tummies, and can be lethally scorched without realizing.
A good heat source for night time is a ceramic heating element (CHE). CHE's are non-light emitting heating units. They get very hot but disperse heat over a very narrow (15" in diameter) and shallow area. The range for a 60 watt CHE is 8" down, the range for a 100 watt CHE is 10" down, the range for a 150 watt CHE is 12" down, and the range for 250 watts is 14" down.
CHE's are not effective in heating large enclosures and a rheostat or dimmer switch may be used for small enclosures so it doesn't get too hot. It is very important that CHE's only be used in porcelain/ceramic light sockets as the amount of heat that they produce is enough to melt regular plastic light sockets.