Red bulbs

From UroWiki

Although there are various beliefs on the use of red bulbs, they are not recommended for use with uromastyx; it is believed that they are able to see the red light, and this has been observed to disturb their sleep. During daylight hours when your uromastyx is active, there should be no visible red light as they come from a climate where it is very bright all day. You should be using UVB bulbs, as well as other bulbs, to provide heat and daylight for your uromastyx.

At night, should your ambient temperature drop below 24'C (75'F), you should use a ceramic heat emitter or a heat projector bulb. This will provide the heat necessary to keep temperatures consistent without having any light to interfere with the uromastyx' sleep habits. In their native habitat, uromastyx sleep in a deep hole at night where no visible light occurs, and therefore you should mimic this as closely as possible in your enclosure.