Why do reptiles need UV light?
A wild reptile typically spends many hours a day basking in the sun, absorbing ultraviolet (UV) light; these wavelengths of light are necessary for the body to manufacture the vitamin D3 required for proper calcium absorption from food. Vitamin D3 is manufactured in the skin and failure to provide UV light can predispose a pet reptile to nutritional metabolic bone disease, an overly common condition of pet reptiles that is fatal if not recognized and treated.
A UV light source should emit light in the UV-B range (290-320 nanometers). UV-A light (320 - 400nm), although important in terms of behavior, does not aid in the manufacture of vitamin D3. Most bulbs sold for use in reptiles provide both UV-A and UV-B. Examples of commercially available UV-B emitting lights are the Reptisun™, Iguana Light™, Power Sun™ (by Zoo Med) and Repti Glo™ lamp by Exo Terra. There are light bulbs with different spectrums of UV light that are available for different types of reptiles, according to their needs. The UV output of a bulb decreases with age, so bulbs should be replaced every six months or as directed by the manufacturer. For UV light to work, it must reach the pet in an unfiltered form, which means that there must be no glass or plastic between the pet and the light. Also, the light should be within approximately 12 inches (30 cm) from the reptile for him to receive any benefit.
"The UV output of a bulb decreases with age, so bulbs should be replaced every six months or as directed by the manufacturer."
Without proper UV light exposure, reptiles routinely develop severe, life-threatening illness. Therefore, it is critical for reptile owners to learn about their reptile species’ specific UV needs and set up their pets’ enclosures accordingly.
Regular exposure to natural, direct sunlight outside (unfiltered through glass) is encouraged and recommended whenever possible. If you take your pet outdoors, make sure you provide a shaded area for the reptile to escape the sun if it chooses so that it does not overheat. Always supervise your pet while it is basking outdoors to prevent escape or attack from other pets or wild animals roaming in the neighborhood.
How much light does my reptile need?
The amount of light your reptile receives each day (called the photoperiod) is very important. In the wild, photoperiod and temperature decrease in the winter and increase in the summer. In captivity however, reptiles who live inside are less subject to these changes in light exposure and temperature variation. Most reptile owners, unless they are encouraging reproductive activity for breeding their pets, which is in part dictated by changes in light and temperature, are advised by veterinarians to keep light exposure and temperature variations consistent in their pet’s enclosure. These constant conditions help reptiles maintain appropriate body temperatures and feeding cycles and stimulate proper immune function, thereby helping keep pets healthy.
Proper lighting is a powerful 'medicine' for proper reptile management. It is also known as an effective appetite stimulant. Consult a veterinarian familiar with reptiles about your pet reptile’s specific needs regarding light exposure.