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.