uvb is practically the artificial sun, they need it works together with calcium to create healthy bones and healthy bearded dragon. uva is basically just your heat. u need the heat to get the enzymes working in the bearded dragon so it can digest its food. i may have uva and uvb mixed up, but thats pretty much what they do. and they are absolutely necessary for a healthy bearded dragon. a good uvb bulb would the reptisun 10.0 (tube)
Actually, UVA and UVB are light not heat. They are just different parts of the spectrum. You don't need to worry about UVA, all bulbs put off UVA. UVB on the otherhand is important for duirnal reptiles, and other animals including humans, because it is involved in Vitamin D3 production which is part of how reptiles process calcium which is why UVB is so important for preventing metabolic bone disease. UVB also stimulates apetite and leads to more energenic reptiles. The Reptisun 10.0 is the most trusted flourecent tube for use with beardies. Avoid the CFL (Compact flourecent coil bulbs) as they have had serious issues with unsafe output. Recently there has been issues with the Powersun and other Mercury Vapor UVB bulbs, but in the past they have been very reliable and produce more UVB and also provide heat.