Do Crested Geckos Need UVB Light?

All reptiles require specific enclosure parameters to remain healthy. These parameters include temperature, humidity, and light.

Crested Geckos are no different. They also need stable temperature, humidity, and a strict light exposure schedule.

But things become a bit more complicated when we’re talking about what type of lights to use in the vivarium. There’s a continuous debate going on about UVB lights in Crested Gecko enclosures.

Some people swear that UVB lights are a godsend, while others claim that UVB is not at all necessary.

It’s easy to get confused by all the contradictory information. The truth is that too much or too little UVB can be equally detrimental in different contexts. Don’t worry, I’ll cover everything you need to know about this topic today.

We’ll go over the benefits, risks, and proper dosing of UVB light. I’ll also talk about whether UVB lights are mandatory, and how to help your Gecko thrive even without UVB.

Hopefully, it will all start making sense by the end of the article.

What is UVB Light Good For?

A reptile enclosure is not complete without a UVB light bulb. And there are multiple reasons why UVB light is necessary for a vivarium. These ultraviolet rays help reptiles synthesize vitamin D3.

Most UVB light bulbs also emit visible light, which helps regulate your Gecko’s circadian rhythm.

The combination of visible and ultraviolet rays can also benefit live plants in the enclosure; this helps you create a natural and lush habitat for your Crestie.

How does a humble light bulb do all this? Let me explain…

– UVB Light and Vitamin D3

UVB light is a precursor for vitamin D3 photosynthesis. Just like us, reptiles have a provitamin D sterol in their skin. When the skin is exposed to UVB radiation, this triggers a chemical process.

Through this process, the provitamin D sterols in the skin convert the UVB light into biologically available vitamin D3. This applies to most reptiles, Crested Geckos included.

As you may know, vitamin D3 is crucial for the absorption and proper use of calcium in the diet. Vitamin D and calcium work together to build and maintain healthy bones.

Without enough vitamin D3, Crested Gecko will develop serious skeletal problems such as spinal deformities and softening of the bones. If left untreated for too long, this issue might even lead to irreversible metabolic bone disease (MBD) and death.

– UVB Lightbulbs and The Circadian Rhythm

Most reptile UVB lightbulbs emit a combination of ultraviolet and visible light. This is great because visible light will help maintain your Gecko’s rest and wake cycle. Consistent visible light exposure throughout the day simulates a Crestie’s natural living conditions.

In the wild, Crested Geckos hide and relax in the shade while the sun is out. They only come out to hunt and explore at night. Without such environmental cues, your Gecko’s circadian rhythm gets thrown out of whack. This can lead to confusion and lethargy.

Luckily, there’s one simple solution. You can include a source of visible light in the enclosure. Keep the lights on throughout the day. Don’t forget to turn the lights off at night! When the lights are out, your Crestie will come out to do its thing (hunting, exploring, and playing).

– UVB Lightbulbs and Live Plants

Contrary to what most people say, UVB light can be beneficial for plants. Plants only require visible light to grow. However, UVB light brings valuable benefits. UVB exposure increases a plant’s photosynthesis abilities, leads to a higher production of flavonoids (plant pigments), and even counteracts the damaging effects of UVA rays.

Even if you keep the vivarium in a well-lit room, you need a UVB bulb to reap these benefits. That’s because UVB light from the sun can’t penetrate through glass. If your live plants aren’t growing as you expected, maybe it’s because they’re only getting visible light. Adding a UVB bulb to the exposure could be a game-changer.

Is UVB Light Bad for Crested Geckos?

No. UVB light by itself is not bad for Crested Geckos. Adequate exposure is even beneficial for your pet’s health. You will only encounter problems when the light is too intense or the exposure is too long.

In this scenario, issues include skin burn, eye problems, lethargy, and dysregulated circadian rhythm.

Many people find it hard to believe, but yes, Crested Geckos can get sunburnt! They have a rich skin pigmentation that protects them from intense UVB rays. But prolonged exposure can still cumulate and cause skin damage.

Intense UVB and visible light exposure can also cause eye sensitivity. The process is self-explanatory. A Gecko’s retina can only absorb so much light until the eye gets irritated and damaged.

If you notice your Gecko spends a lot of time hiding in the shade or keeping its eyes closed, the light might be too intense.

Finally, as I’ve already mentioned before, excessive visible light exposure can also mess up your Gecko’s sleep and wake cycle.

This will cause lethargy, stress, and confusion. If you use a UVB light bulb with visible light, you’ll need to establish a strict schedule. Remember, your Gecko needs shade and darkness too!

Advantages of UVB Light for Crested Gecko

When dosed properly, UVB light is both safe and beneficial for your Crested Gecko. Appropriate UVB light exposure offers multiple perks you won’t want to miss.

Here are some of the considerable advantages of UVB light for Cresties:

  • UVB supports natural vitamin D3 synthesis.
  • It improves your pet’s immune system.
  • UVB exposure improves fertility in Geckos.
  • It simulates a Gecko’s natural environment.
  • The enrichment and health benefits lead to increased well-being.
  • UVB light might be safer than vitamin D supplementation.

The last point is especially important. Supplementation with vitamin D3 is useful, but not without risks. Dosing the supplement is difficult. But overdoing it on the vitamins is easy. Remember, vitamin D3 is fat-soluble.

Fat-soluble vitamins consumed in excess will be stored in your Crestie’s body, as opposed to being peed out.

Too much vitamin D over the long term can lead to liver and kidney problems, skeletal issues, and overall poor health. The good news is that your pet can’t overdose on vitamin D from light.

The Gecko’s body keeps a tight balance and only produces what it needs. Thus, UVB light might be safer than supplements to reach nutrient adequacy.

How Much UVB Light Can Crested Gecko Have?

As a bare minimum, Crested Geckos don’t need UVB light at all. As long as your Crestie receives vitamin D3 supplements, UVB light is not necessary.

However, if you want to include UVB lights in the enclosure, a good range of exposure is 4-6 hours per day. This is enough for your pet to reap the benefits without overdoing it or overheating the enclosure.

Besides the duration, you’ll also have to consider the quantity of the exposure. Crested Geckos are nocturnal and crepuscular animals. They do best in lower-light settings. Suitable UVB bulbs for Crested Geckos have a light output in the range of 2-5%. Avoid lightbulbs with high UVB outputs, as these might be too intense for your pet.

Can Crested Geckos Live Without UVB?

UVB light brings many health benefits to your Crested Gecko. However, Cresties can also live comfortably without UVB exposure. But there are two conditions to make this work:

First, you must supplement their diet with vitamin D3.

Without UVB exposure, Geckos won’t synthesize the vitamin D they need. This will lead to poor calcium absorption and subsequent bone problems. To counteract this issue, you should include supplemental vitamin D3 in the Gecko’s diet.

You’ll find plenty of reptile vitamin D3 products, usually in powder form. I recommend Repashy. Their range has nutritionally complete meal replacement powders with various D3 concentrations.

If you plan to feed your Crestie insects, you should also buy vitamin D3 supplemental powders for dusting.

Secondly, you must still expose your pet to visible light.

Your Gecko might not need ultraviolet light, but it still needs some visible light. You need it to simulate the Crestie’s natural habitat in the wild. Your Gecko will organize its resting and activity around environmental cues such as temperature and sunlight.

If you keep your Gecko in a dimly lit room, consider purchasing an incandescent lightbulb. These come in a variety of intensities, and you can even choose the light color if you prefer cool or warm light.

Just remember to keep the light source further away from the vivarium to avoid the glass from overheating. A proper duration of visible light exposure ranges from 4-6 hours a day.

Does UVB Help Crested Geckos Grow?

Maybe. I say “maybe” because I couldn’t find any actual studies on it. However, many Crestie owners report better growth, increased appetite, higher activity levels, as well as an increased lifespan in their UVB-exposed Geckos.

It’s not hard to believe, since UVB does have documented health benefits in reptiles. These include better nutrient status, a stronger immune system, increased fertility, and general wellbeing.

And let’s not forget that UVB light helps your Crested Gecko produce vitamin D3 and absorb calcium. These micronutrients are essential for the formation and maintenance of strong, healthy bones.

Combined with a nutritionally-adequate diet, UVB light could lead to better and faster growth.

What are the Risks of Giving Too Much UVB to Crested Geckos?

As I’ve previously stated, UVB light in itself poses no danger to your Gecko’s health. Proper exposure to UVB has multiple benefits for your Gecko’s physical and mental wellbeing.

But there’s also too much of a good thing. Excessive UVB exposure brings various risks, including:

  • Skin dryness and itchiness
  • Skin burns
  • Eye irritation or eye damage
  • Dysregulated circadian rhythm
  • Lethargy
  • Stress
  • Shortened lifespan

UVB light has a very short wavelength. This means the light doesn’t penetrate the Gecko’s skin very deeply. This is good because the light gets absorbed by the cells to get converted into vitamin D3.

But it’s also bad because this makes UVB rays more potentially damaging to the shallow layers of the skin.

Prolonged exposure to short-wavelength UVB can cause cumulative skin damage. Over the long term, this can lead to skin dryness or even skin burns in Crested Geckos. This skin damage can also cause itchiness and might even affect shedding.

Excess UVB light exposure can be equally damaging to the eye’s retina. UVB rays might cause cell damage and irreversible retinal degeneration.

Besides, excess exposure to light of any kind will disrupt your Crestie’s sleep and wake cycle.

If your Gecko can’t rely on environmental cues to organize its rest and hunting schedule, this might lead to lethargy and stress.

Chronic stress alone can lead to many unfavorable outcomes such as lack of appetite, weight loss, poor immune system, and even a shorter lifespan.


UVB light helps reptiles synthesize vitamin D3. This nutrient is crucial for building and maintaining healthy bones. But Crested Geckos don’t need UVB light, as long as their diet contains enough supplemental vitamin D3.

This nutrient is easy to include in the Gecko’s diet. Most commercial meal replacement powders contain vitamin D, as do powder supplements for dusting.

Besides vitamin D production, UVB light also brings other potential health benefits, including increased fertility, a better immune system, and overall well-being.

On the flip side, too much UVB light exposure can lead to skin dryness and burns, eye damage, lethargy, and stress. To keep the right balance, you should use a low-output UVB bulb.

Any bulb with a 2-5% UVB output, used for 4-6 hours a day provides sufficient exposure without increasing the risk of side effects.

avatar William
William is a respected pet enthusiast with expertise in reptiles and birds. With extensive experience caring for these animals, he shares his knowledge through engaging and informative articles in various publications. He is an active member of pet-related organizations, volunteering regularly at shelters and promoting animal welfare and conservation. read more...

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