This whole area of UV needs and appropriate sources is much debated. In the past, fluorescent lighting has been the only source of indoor full spectrum lighting, but I understand that there are now incandescent full spectrum bulbs available. In addition to full spectrum light, the tortoises need a heat source. I like to use a combination of top and bottom heat sources. These lights are controlled by rheostats so that seasonal adjustments can be made without changing light bulbs.
Bottom heat is provided by several means.
The tortoises readily climb onto these low platforms. A similar heating box can be made from 12 or 16 inch wide Flexwatt panels. If the cage floor is thin enough to allow sufficient heat transfer a heating devise can be placed directly under the cage. As a precaution I have developed ingenious ways of protecting any electrical cords located inside the pens. Unfortunately, I do not have enough space to describe these marvelous devices in the scope of this article.