A bearded dragon's lighting set-up should mimic what the reptile would get in the wild as closely as possible. To achieve this, you should first know what a natural environment for a bearded dragon is.
What Kind of Lighting Does a Bearded Dragon Need?
Being from the desert, beardies in the wild receive high levels of UVB and heat from the sun on a daily basis. In order to best mimic this in an indoor enclosure, high UVB output lightbulbs must be used in addition to heat bulbs.
What Produces UVB Rays?
Aside from sunlight (not filtered through a window), there are a couple of different sources of that give off invisible UVB rays. Fluorescent bulbs and mercury vapor bulbs are the two sources most commonly used in the pet world.
Fluorescent Bulbs
Special fluorescent bulbs that fit into fluorescent fixtures give off varying levels of UVA and UVB (usually given as percentages) rays. These full spectrum bulbs run out of rays before the lights actually burn out, therefore they need to be replaced per manufacturer recommendations, or every 6 months.
Bearded dragons need an 8-10% output of UVB rays which should be clearly marked on the bulb packaging. These bulbs are to be placed 6-8 inches from where your beardie can get to to soak in the rays. Also make sure the bulb is not placed on a plastic, plexi-glass, or glass surface. These types of substances will block the rays from penetrating into where your reptile needs them. Newer research also shows that the typical metal mesh screen commonly used for reptile tanks blocks a significant amount of UVB rays as well. Therefore, try to mount your bulb on the inside of the enclosure to make sure as many rays reach your beardie as possible.
Mercury Vapor Bulbs
Mercury vapor bulbs serve more than one purpose for your bearded dragon. They emit both UVA and UVB rays and they also provide heat for your enclosure. This allows you to use only one bulb to provide both heat and the important UVA/UVB rays in place of the usual two.
These bulbs last a great deal longer than fluorescent bulbs and heat bulbs and although they cost more, seeing that they last longer usually makes them worthwhile. Some people even note better appetite, coloration, and energy in their beardies while using mercury vapor bulbs.
There is some discussion in the reptile community that mercury vapor bulbs can be dangerous to reptiles because of the intensity of the UV rays produced by these bulbs. Despite the worries, a number of reptile owners have never had a problem. If you do decide to go with a mercury vapor bulb, be sure to provide plenty of shade opportunities in the enclosure, use a ceramic socket for the bulb, and keep a distance of 12-24 inches between your reptile and the bulb for safety reasons. This bulb is best used for large spaces that allow you beardie to roam.
Compact Fluorescent Bulbs
These bulbs do all the same things as the regular fluorescent bulbs but they fit in an incandescent fixture. They also use less energy than a fluorescent bulb and should last longer but some research shows the UV is much too high for reptiles and they don't last as long as they should.
