While most pet lizards require heat or ultraviolet lights for their cage, these lights must be cycled on and off in a manner that mimics your pet's native habitat. The amount of light your lizard receives on a daily basis -- called his photoperiod -- is an important aspect of husbandry; improper photoperiods can cause stress, maladaptation and illness.
Day and Night
Because they live close to the equator and experience nearly equal days and nights, tropical reptiles should have a photoperiod of about 12 hours, and it should remain such all year long. By contrast, animals from temperate latitudes receive a varying amount of sunlight throughout the year. Provide temperate animals with about 14 hours of light in the summer; reduce this to 10 hours of light per day in the winter. Temperate animals should have days and nights of approximately the same length during the spring and fall. Maintain the photoperiod by using an automatic timer switch to avoid having to turn the lights on and off manually.