The Importance of UVB Light and Sunshine

For diurnal (day-time) reptiles, not providing the proper lighting is like not providing fish with water. They aren't thrashing around but they are doomed to perish none the less. So the importance of making sure your reptile has proper lighting cannot be understated. It extends far beyond the need for heat, which is also vital, but also to the need to replicate the full spectrum of light that the sun is outputting. In this blog, I will be talking about the all-important light: the ultraviolet spectrum, particularly UVB.

Basking bulbs not only provide reptiles with a heat spot in which to bask and warm up, but they provide the visible spectrum of light that mimics daylight. Just as the mood of people declines when they do not experience daylight, so do reptiles. So it's important to use white light bulbs, and not blue or red when keeping a diurnal reptile.

However, the UVB is the spectrum of light that we humans cannot see but that is supremely important to the long-term health of reptiles. Like us, reptiles make the vital vitamin D3 in their skin when exposed to the UVB from the sun, and this vitamin in turn allows calcium to be absorbed by the bones. Therefore, when this light spectrum is not provided they cannot absorb calcium as efficiently and a young reptile will begin to show calcium deficiencies in the form of bone deformities (bowing of the long bones in the arms and legs, bone fractures, curving in the spine and tail, etc.) and loss of muscle control. To learn more about the effects of different vitamins and minerals in the body of  chameleons, refer to  this blog: Chameleon Physiology & Supplements

A chameleon showing severe calcium deficiency deformities and fractures. Photo from this forum thread:  What MBD Looks Like, Chameleonforums.com

Even though we use powered vitamin D3 as a supplement, studies in scientific journals show that providing D3 only via diet is not an effective long-term solution and that the reptile will develop deficiencies anyway (and worse, artificial D3 overdoses, which can lead to the calcification of the tissues). The only way to ensure that your reptile is getting the adequate levels of natural D3 is to provide a good UVB light from a reptile brand. People are often reluctant to purchase them because they can be a little expensive but they are vital, and can be found cheaper from online sources if one knows where to look. Providing one is the best way to make sure your reptile's bones and system absorb calcium properly. 

CHOOSING A UVB BULB

This can be confusing, but it doesn't have to be. The most commonly recommended brand is Zoo Med Reptisun 5.0 or 10.0, which is easily available. A cheaper bulb is the Exo Terra Reptiglo 5.0, but I would not buy these (at least go for the 10.0 bulb) because its UV output is really minimal, in my opinion. 

Then there are very powerful (and slightly more expensive bulbs) from brands such as ReptileUV or Arcadia, but these are excellent bulbs and have much more powerful UV outputs. The Megaray bulbs by ReptileUV are better for free ranges or huge cages, as they are both heat and UVB bulbs and are very powerful. These would roast a chameleon in a small cage who cannot escape the light. The Arcadia 6% or 12% bulbs are only UVB lights and provide much stronger levels than the common brands and therefore last much longer between replacements. 

With any UVB bulb it is important to provide areas of shade so the chameleon can choose whether to be in the light or not. 

NATURAL SUNSHINE

In addition, if your weather allows, I believe that getting your reptiles outside for some natural sunshine is one of the best things you can do for them. There isn't an artificial bulb available that recreates the sun in everything that it provides, so outside is when you usually see your reptiles (chameleons particularly) at their very best, color-wise. While these commercial bulbs provide the adequate UVB output for reptiles to do well throughout their lives, nothing compares to the sun itself. 

 Below is a graph showing the UVB readings throughout the day at different locations across the planet. The graph comes from UV Guide UK, which is an excellent source to not just buy a UV meter but to learn about the different UV readings, either outside or by different bulb brands. 

SOURCE: http://www.uvguide.co.uk/uvinnature.htm.
But graph shows UVB readings throughout the day at different locations across the planet. 

In my particular location, I am looking at the biggest orange line, the one with squares that corresponds with Sarasota, Florida. The only time the UVB output is at 30 (the typical output of a new UVB bulb, like Reptisun) is before 8am and after 4pm. This is very low compared to the almost 250 it reads at the height of the day. In longitudes corresponding to the northern hemisphere equivalent of southern Africa and Madagascar, the daily maximum is even higher! Therefore, providing your chameleon with at least 20 minutes of natural sunlight during most of the day as often as possible will give reptiles a healthy boost of natural UVB.*

*IMPORTANT: Make sure you provide your chameleon with shaded areas and access to water in case it is very hot out. While you want them to get some sun, you don't want them to overheat in the process. And never ever have them outside in a glass tank!  

KEEPING REPTILES OUTSIDE?

If you are reading this and wondering, "could I keep my reptile outside instead of indoors?" the answer is yes! If your climate meets your animal's temperature and humidity needs and if the enclosure provides shade, water, hiding places, and protection from wildlife like raccoons or hawks. I will keep my chameleons in outdoor cages for days or weeks at a time and they do really well, but my climate here in Florida will be very different from that of Montana or Germany, so your climate needs to be considered very carefully.