Reptile Lighting Overview
Reptiles are “cold-blooded” and cannot generate their own body heat. They must rely on external temperatures to regulate their internal temperature and manage their metabolism. In the wild, reptiles have the choice of moving into and away from an area with the temperature they need (e.g. sun or shade), changing locations and adjusting the temperature as necessary. In captivity, reptiles need an artificial thermal gradient. This is particularly important to ensure the maintenance of certain key processes such as digestion of food.
Placing heat sources at one end of the enclosure and using a thermometer to accurately gauge, will create thermal temperature gradients. There are several ways to heat parts of your terrarium enclosure. Overhead heating (such as incandescent lamps) resemble nature the most. Under tank heating (such as reptile heating pads) can also be very effective. You can also use ceramic heating elements that are a very powerful source of heat. Always shield the reptile from the heat source and never use anything which may come into direct contact with the reptile.
In general, temperatures can be dropped at night to mimic conditions in the wild, although a nighttime minimum temperature must still be maintained. A basking spot is usually part of the thermal gradient, providing the top range of temperatures for your particular reptile species. It is usually provided by an incandescent lamp over a specific spot at one end of the enclosure (e.g. on some rocks or driftwood). Make sure that the wattage is appropriate for your reptile.
Aside from the heat, many reptiles also need sufficient lighting and a very specific type of UV light to thrive. These reptiles include all turtles, tortoises, the vast majority of lizards, snakes, and amphibians. Without exposure to UV light, these reptiles cannot produce Vitamin D3 effectively. This leads to problems with calcium in their metabolism. By exposing the skin to natural sunlight or an artificial UV light source, the reptiles can produce the necessary Vitamin D3 within their bodies. Supplementation of Vitamin D3 via the diet is possible but not as effective.
Even if your reptile does not need UVB light to maintain health – such as many snakes and nocturnal lizards - it is still important to provide a regular night-day cycle that utilizes UVA lighting, for psychological well-being and to prevent undue stress to the animal.