Why do reptiles need UV light?
Ultraviolet (UV) light is necessary for reptiles to manufacture vitamin D3, which is required for the intestines to successfully absorb calcium from food. Diurnal wild reptiles typically spend many hours a day basking in the sun, absorbing this light.
Crepuscular reptiles (active during twilight) and nocturnal reptiles (active at night) may not openly bask, they too increase their vitamin D concentrations following UV exposure in captivity (e.g., leopard geckos). Vitamin D3 is manufactured in the skin, and failure to provide UV light can predispose a pet reptile to nutritional secondary hyperparathyroidism, also known as metabolic bone disease (MBD). MBD is a common condition of pet reptiles that can be fatal if not recognized and treated early in the disease process.
A UV light source should emit light in the UV-B range (290-320 nanometers). UV-A light (320 - 400nm) does not aid in the manufacture of vitamin D3, although it is important for behavior. Most bulbs sold for reptiles provide both UV-A and UV-B. Examples of commercially available UV-B lights are the Sun Glow™ (by Fluker Farms), Reptisun™, Iguana Light™, Power Sun™ (by Zoo Med), and Repti Glo™ lamp by Exo Terra. There are a wide variety of light bulbs with different spectrums of UV light that are available for different types of reptiles, according to their needs. The ones listed above are the most recommended by professionals.
"It is critical for reptile owners to learn about their reptile’s species-specific UV needs and set up their pet’s enclosure accordingly."
The UV output of a bulb decreases with age, so bulbs should be replaced every 9–12 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 UV light should be between 9 inches and 15 inches (30 cm) from your reptile to provide any benefit. Keeping the bulb too close can predispose the reptile to photokeratitis, skin damage, or neoplasia (abnormal cell growth).
Without proper UV light exposure, reptiles may develop severe, life-threatening illness due to MBD. This condition may cause bone swelling, bone fractures, kidney disease, and muscle tremors. Therefore, it is critical for reptile owners to learn about their reptile’s species-specific UV needs and set up their pet’s enclosure accordingly.
Regular exposure to natural, direct sunlight outside (unfiltered through glass) is encouraged and recommended whenever possible. If you take your pet outdoors, it is important to make sure the ambient temperature is appropriate for that species so that your reptile does not become overheated or chilled. Also, 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 both decrease in the winter and increase in the summer. In captivity, however, reptiles who live inside are less subject to these changes in reference to light exposure and temperature variation.
Veterinarians advise most reptile owners to keep light exposure and temperature variations consistent in their pet’s enclosure, unless they are encouraging reproductive activity for breeding their pets, which is in part dictated by changes in light and temperature. These constant conditions help reptiles maintain appropriate body temperatures and feeding cycles and stimulate proper immune function, thereby helping keep pets healthy. (Photo courtesy of Greg Rich, DVM)
Proper lighting is a powerful medicinal tool for proper reptile management. It is also known as an effective appetite and immune stimulant, as well as providing known benefits for calcium absorption. Consult a veterinarian familiar with reptiles about your pet reptile’s specific lighting needs.
