When reptiles and amphibians are domesticated, most species will require special UVB lights within their enclosure to make up for a lack of access to direct sunlight.
UVB (Ultraviolet B) is a type of light emitted by the sun that helps animals produce vitamin D3. (If you have ever heard of Seasonal Affective Disorder in humans, this is caused by a vitamin D3 deficiency due to lack of UVB sunlight!)
Each species of reptile and amphibian benefits from differing UVB light levels, spaced at varying distances from their basking area. Nocturnal species will need this light during the night and vice-versa for those awake during the day. Consult your veterinarian about the optimal delivery of light for your exotic pet.