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Full Spectrum Lighting: What is beneficial and what is dangerous

Reptiles are cold blooded meaning they require external warmth to thrive. When the ambient temperature gets too cold they simply shut down and go inactive. Where adapted to do so, this can be a strong survival tool to wait out the winter where they can re-emerge in the warmth of spring and summer. In the more tropical areas where the winter is mild, they can tune their habits to coincide with the sun and flourish all year long.  As reptile keepers, it is our challenge to simulate those needs without direct access to the sun and often times in climates that are inhospitable to our reptilian friends.

In order to provide them with the full spectrum of needs as the sun provides, we must first understand what exactly the sun contributes to their wellbeing, and also understand what dangers that presents. It might surprise you that sound and light have travel in much the same way, through waves. Deeper sounds have slow waves, higher sounds have faster waves. The distance between the peaks of each wave is its frequency (how often the peak happens in a given time). Sound waves travel slowly and light waves travel much faster.

But what does all this mean in relation to our reptiles? It’s actually not very complicated and much of it also relates to us humans as well. We can break up the light spectrum into six types of light, four of which we need to provide and two which we need to avoid. At each end of the spectrum are dangerous types of light; Ultraviolet C which borders X-ray which is largely filtered out by our ozone layer and Microwave that as you know can cook your food. In between these two extremes are the most common types of light in our daily lives Ultraviolet A and B, Visible light, and Infrared.

UVC: It is important that you don’t use just any light with your reptile. Even thought our ozone filters out dangerous UVC waves, some of our manmade lights can reintroduce it. This is particularly dangerous to reptiles as UVC can kill cells and is a leading cause of blindness in many captive kept lizards.

UVB: This is the one you hear the most about. It is responsible for the initial conversion of cholesterol in the skin of reptiles to the building blocks that can be converted to vitamin D3. The human eye cannot see this spectrum but many reptiles can which gives them special perception that we lack. None of your household light bulbs produce UVB, it takes a special process with special types of glass to create a bulb that can produce this wave length. It is also important to note that most plastic and glass do not allow UVB to pass through unless they were specially designed to do so. Most household and terrarium glass is actually designed to block uv rays.

UVA: This band of light is responsible for the conversion of UVB's pre- vitamin D3 into vitamin D3 which ultimately benefits your reptiles. This vitamin helps to bind calcium. Your lizard has the special ability to self regulate the exact amount of D3 it needs which makes providing this light much safer than trying to provide a balance through supplements.

Visible Spectrum: This is the type of light human eyes can see. It is responsible for all the colors of the rainbow we perceive in our daily lives but it is only part of the broader spectrum of light that reptiles can see. When you buy colored bulbs, these are more for you than they are for the reptile. Reptiles also use this type of light to see like we do.

Infrared:  This is side of the light spectrum that produces heat. It is a special kind of light that can penetrate skin and finishes converting the pre-vitamin D3 building blocks into Vitamin D3. This final step is essential for reptiles to bind any calcium they have consumed onto their bones so that they don’t develop life threatening diseases like metabolic bone disease. Additionally, this is another spectrum of light that some reptiles have adapted to seeing, the most common being pit vipers like pythons and rattlesnakes.  Anything that emits heat with emit ultraviolet light. No matter how dark the visible light is, if you are warm you cannot hide.


Microwave: This is exactly what it sounds like, waves so far to the end of the spectrum that they produce intense heat that cooks tissue. Needless to say this is extremely dangerous.