Reptiles need exposure to UVB rays to produce vitamin D3, which is essential to their ability to absorb calcium. Unlike people, reptiles  cannot produce their own Vitamin D3, so they must depend on UVB rays. Without Vitamin D3, a reptile will not have a sufficient supply of calcium even if it is given a supplement, a condition that will lead to the development of a metabolic bone disease.

UVB rays should be provided to a reptile by a fluorescent bulb that also provides UVA rays.  There are a variety of full spectrum lights available at PSP that emit UVB light in combination with UVA light. Fluorescent lamps producing UVB rays should be replaced every six months, since they lose their effectiveness over time.

Glass blocks out UVB light, so overhead light sources should be kept behind a wire mesh cover, not a glass or acrylic tank top. This light source should be within 12 inches of the animal.

In most cases, full spectrum light should be operated on a 10-12 hour on/off day/night cycle. Consult cares sheets for details on lighting requirements for specific animals.