Bearded dragons need daily exposure to UVB rays in order to maintain their health but is it possible for a bearded dragon to get too much UVB?

In this post, we will dig deep and discover if bearded dragons can get too much UVB, and if so, what the signs and consequences of too much UVB are.

So, can bearded dragons get too much UVB? Bearded dragons can be overexposed and get too much UVB. They will seek UV as needed biologically and usually, overexposure will happen if they cannot move away from the UVB rays. Enclosure set-up is vital to avoiding overexposure. 

Read On to Find Out…

Can Bearded Dragons Get Too Much UVB? (More Info)

Bearded dragons can indeed be exposed to too many UVB rays in certain circumstances. The importance of enough UVB is widely documented but the effects of too much UVB is less so. 

Ultraviolet or UV comes in 3 different spectrums, UVA, UVB, UVC. UVA and UVB are the two that are most important for reptiles. UVA promotes heat and assists digestion and UVB is essential for the conversion of vitamin D.

Bearded dragons are experts at self-regulation if provided with the correct environment. 

Their behaviours are basic and driven by survival as conserving energy is important for ectotherms (cold-blooded reptiles).

When they are cold, they will seek heat. When they are hungry, they will look for food. If they feel too hot, they will move away. If a bearded dragon feels it is receiving too much UVB they will look to move away. 

If they cannot move away or the UV lamp is too close to the basking area your bearded dragon may get too much UVB – both absorbed and in their environment.

When you keep a bearded dragon in captivity you should aim to keep the environment as close as possible to the natural environment as bearded dragon’s life in the wild. Wild behaviours include basking both for heat and absorbing ultraviolet rays from the sun.

Is UVB Essential For Bearded Dragons?

Bearded dragons, as well as other reptiles, require many different elements of care to remain healthy when compared to animals such as cats and dogs but is UVB really that important?

So, is UVB essential for bearded dragons? UVB is essential for bearded dragons. UVB assists in a healthy metabolism, the absorption of calcium and healthy bones and blood. A lack of UVB can cause serious health issues including metabolic bone disease and cancers and restrict health growth and development.

Most species of reptiles including bearded dragons are not able to metabolize and use vitamin D when it is present in their diets. 

To use vitamin D they need to convert it into vitamin D3 using a process called the D3 cycle. This cycle is fairly complicated but in short, they need both UVB exposure and warmth to complete this process.

Vitamin D is vital to reptiles for the absorption of calcium from the diet. Calcium is vital to blood and bone health and calcium deficiency can have severe consequences, most famously metabolic bone disease which can cause deformities, but also many types of cancers in the skin and blood.

UV is naturally supplied from the sun for all wild diurnal animals, but for those in captivity, UVB can be provided to your bearded dragon by the use of a special UV lamp in the enclosure. 

These lamps will emulate the rays from the sun and in conjunction with heat, they will provide an alternative to the benefits of the sun.

Providing UV lights also benefit the environment your beardie lives in, minimizing fungi and bacteria growth. 

UV rays are also scientifically proven to stimulate the brain to produce mood-improving chemicals.

The UVB bulb we recommend is the Reptisun 10.0 UVB bulb. 

You can head over to our recommended lighting page to learn more about this bulb

or check it out directly over at amazon below…

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What Will Happen If My Bearded Dragon Gets Too Much UVB?

So we now know that UVB is essential for the health of bearded dragons, it does not mean we should provide a constant and high-output source of UV. 

Although it’s of high importance to provide enough UV, there is such a thing as too much UVB.

So, what will happen if my bearded dragon gets too much UVB? If your bearded dragon gets too much UVB it may suffer from photo-kerato-conjunctivitis, hypercalcemia or hyperkeratosis. A huge overexposure may result in similar effects as a UVB deficiency, except they will result in renal failure from hyperparathyroidism.

Anyone who has spent a day at the beach without sunblock will be well aware of the effect of excess UVB exposure on our skin! But your reptile has a different relationship with the sun and overexposure to UVB will cause issues different to a simple sunburn.

These side effects may sound complicated and difficult to understand at first so let’s break each of them down and see what they mean…

1. Photo-Kerato-Conjunctivitis

Photo-kerato-conjunctivitis (PKC) is a mouthful of a name so let’s break it down. “Conjunctivitis” refers to any inflammation of the thin layer of tissue that sits over the eye and under the eyelid. 

“Kerato” refers specifically to the cornea and “photo” relates to UV rays.

Put this together and PKC is UV damage to the corneas, like a sunburn on the eye. 

Doesn’t sound pleasant right! In humans, this is seen most in mountain-goers as it is also called “snow blindness” and caused by the reflection of UV from the snow. 

Too much UVB exposure to the eyes of your bearded dragon can cause this painful problem, luckily it is superficial and once the source of UV is removed it will heal quickly. 

Prolonged PKC can cause ongoing cataract issues and if mismanaged can result in the surgical removal of the eye.

2. Hypercalcemia

Exposure to too much UVB can cause hypercalcemia, which is simply too much calcium in the blood. Too much UVB causes too much vitamin D3, which results in too much calcium.

A dangerous excess of calcium can lead to calcium build-up and deposits through the body, in particular the kidneys which can mineralize and result in hyperparathyroidism. 

This disease then causes more synthesis of calcium and your bearded dragons body can quickly shut down.

Many beardie owners are highly concerned about the effects of lack of D3 and calcium that they provide an excess, both in lights and in dietary supplementation.

It pays to be aware of all the sources of D3 and calcium you are providing and look at your husbandry as a big picture, not in individual pieces or you may risk excess of these minerals.

3. Hyperparathyroidism

There is two types of this disease that can affect your bearded dragon: secondary nutritional, which is associated with not enough calcium in the diet or not enough UVB in the environment and secondary renal which can be caused by excess UVB.

Most reptile owners associate this metabolic bone disease with UVB deficiency, not too much UVB. But as outlined above excess calcium can cause calcification of vital soft tissue causing secondary renal issues.

This is a bone disease as it can cause brittle or deformed bones and can ultimately lead to total kidney failure.

4. Hyperkeratosis

Overexposure to UVB rays can also cause this alignment which results in the excess thickening of the skin. 

This is a protective response of the skin and can be beneficial in some instances but if this is constant is can cause uncomfortable skin lesions and callouses or even crusting of skin around the nares or mouth, restricting eating or respiration.

What Are The Signs That a Bearded Dragon Has Had Too Much UVB?

Clearly, we do not want to be in a position where our bearded dragon is exposed to any prolonged periods of too much UVB as it can have life-threatening consequences. 

Below we will go over some of the signs to look for when you are concerned that your bearded dragon has had too much UVB.

So what are the signs that your bearded dragon is getting too much UVB? The signs that a bearded dragon is getting too much UVB are:

  • Eyes swollen, closing or squinting
  • Eye cloudiness or limited vision
  • Skin thickening or darkening
  • Evasive behaviour
  • Lethargy

Let’s now take a look at these signs in more detail…

1. Eyes Swollen, Closing or Squinting

The eyes are tell-tale first signs of too much UVB. Eyes are the first to react to overexposure and they are the most delicate exposed part of a bearded dragon, the rest is covered in protective scales.

Your UVB output may be too high if your bearded dragon is constantly keeping its eyes closed as it basks under the lamps or shows a light sensitivity with squinting.

Here’s our easy to follow guide that walks you through the heating and lighting setup for your beardie…

The eye may become swollen and red if the UVB has created a trauma in this area, causing PKC.

2. Eye Cloudiness or Limited Vision

The eyes response to this trauma is to send cells to the area to protect and heal the eye. This can result in the visual cloudiness of the eye. 

These cloudy cells will limit vision and you may notice your bearded dragon is less responsive in one eye, test vision by using live food and see if they react to the movement.

3. Skin Thickening or Darkening

As discussed above too much UVB can result in hyperkeratosis, which is a thickening of the skin as a result for protection purposes.

Visual signs of this include darkening of the skin, skin lesions and clumping of skin near eyes, nares and mouth.

You may also notice that your bearded dragons shed is abnormal and retains in thickened areas such as areas the legs and joints.

4. Evasive Behaviour

Your bearded dragon knows better than anyone what its body wants and needs and when it feels it has had enough UVB is will try to get away from the UV source. 

If it is unable to get away from the source, you may see it stressing and acting evasively including climbing the glass or wedging itself in tight spaces.

Recommended Reading: The 10 Reasons Your Bearded Dragons Isn’t Basking

5. Lethergy

An unusual lack of activity is a common result of many health issues. 

Serious lethargy and unresponsiveness is a sure sign your bearded dragon’s body is struggling with something, coupled with the above symptoms, you may deduct excess UVB as the cause.

What Are The Causes Of Too Much UVB  In Bearded Dragons?

Keeping an environment perfect for your beardie can be a challenge. 

Knowing what can cause too much UVB for your bearded dragon will help you create a wonderful environment so your beardie stays healthy. Below are some common causes of too much UVB.

So, what are the causes of too much UVB in bearded dragons? The causes of too much UVB in bearded dragons are:

  • Bulb too close
  • Poor quality lamp
  • Poor lamp placement
  • No hides
  • Lamp on too long

Let’s now take a closer look at the causes of UVB in bearded dragons…

1. Bulb Too Close

UV dissipates through the air, the further you are away from it the less effect it will have. 

This is why we construct and design furniture for bearded dragon enclosures that slants upwards and allows the bearded dragon to get closer to the lamp. This way they can self regulate.

If the bulb is too low to the lowest point of the enclosure, the UVB will be too high and the bearded dragon cannot move itself any lower. 

The same goes for if the lamp is in the centre of the enclosure is creates less of a gradient of UV exposure, leaving no end that has less UV, forcing your bearded dragon to be exposed.

2. Poor Quality Lamp

Some lamps can be of poor quality with the wrong type of glass or white coating. The glass and the coating are designed to filter the UV rays from the emitter itself so if they aren’t suitable they can put out too much harsh UV.

Damage can also occur to even good quality lamps, the coating can be chipped or rubbed during manufacturing or transport so check lamps are not damaged before using them in your bearded dragon enclosure.

Ideally, lamps should be replaced every 6 months or to the manufacture’s guidelines.

3. Poor Lamp Placement

Your UV lamp should always be placed overhead and not on the side of the enclosure. This replicates the direction the sun naturally comes from in wild environments.

Bearded dragons are well adapted to their environment and their distinct eyebrow ridges are an evolutionary adaptation to protect their eyes from too much sun and UV exposure.

Placing the lamp on the side will allow the UV rays to get directly into bearded dragons eyes are cause issues a lot faster.

4. No Hides

As mentioned, reptiles are masters of self-regulation if they are provided with the right environment.

Overexposure to UVB most commonly occurs when bearded dragons cannot physically get away or shield themselves from the UV lamp.

A dull and flat enclosure can result in a lack of refuge from damaging rays.

You can learn more about how important hides are for beardies over at our new article.

Here’s a list of our favorite hides that your beardie will love and feel safe as they can fit their whole body in the hide…

Exo Terra Reptile Cave, Medium
Exo Terra Reptile Cave, Medium
Provides secure hiding place; Natural look integrates in any type of terrarium; Prevents stress
Exo Terra Terrarium Decor Primate Skull
Exo Terra Terrarium Decor Primate Skull
Prime skull reptile cave; Extremely realistic looking skull terrarium decor; Offers multiple entrances and exits for easy access
Amazon Prime
Exo Terra Terrarium Decor Croc Skull LQ, for Reptile and Amphibians
Exo Terra Terrarium Decor Croc Skull LQ, for Reptile and Amphibians
Crocodile skull provides secure hiding place for reptiles and amphibians; Ideal for desert and rainforest terrarium setups
Amazon Prime

Last update on 2023-11-22 / Affiliate links / Images from Amazon Product Advertising API

5. Lamp On Too Long

Bearded dragons get their light and UV from the sun and in their natural habitat of Australia, there are day and night cycles.

Overexposure to UVB can be due to the light schedule being wrong and the light being on much too long. 

Not only will the light be disruptive to sleep if the light stays on constantly, but UVB exposure will also be doubled.

How Can I Prevent My Bearded Dragon From Getting Too Much UVB?

The good news is that simple housing and care methods are enough to prevent overexposure to UVB for your bearded dragon.

So, how can you prevent your bearded dragon from getting too much UVB? You can prevent your bearded dragon from getting too much UVB by:

  • Correct lamp placement
  • Dynamic enclosure
  • Check furniture
  • Correct photoperiod

Here’s a closer look at each of these methods…

1. Correct Lamp Placement

Ensure your lamp is placed directly overhead in the enclosure and never to the sides. 

The lamp should not be centred nor cover the entire length of the enclosure. 

Place the lamp to one end to create a temperature, light and UV gradient and your bearded dragon will self regulate.

It’s worth investing in a nifty little device called a UV reader which can measure ultraviolet light. Measure all through the enclosure to ensure there is an adequate distribution and your lamp is placed correctly.

UV does not penetrate glass so the lamp needs to be below any glass covering. Mesh tops can also limit UV depending on the size of the mesh but can limit up to 30% of UVB.

2. Dynamic Enclosure

Creating an interesting and dynamic enclosure is valuable in many ways to your dragon’s mental and physical health but ensuring there are hides so your bearded dragon can escape whenever it needs to is vital.

3. Check Furniture and Substrate

Above we discussed PKC and how it is related to snowy environments in humans. 

Check all furniture and substrate that goes into an enclosure to ensure it does not have a reflective quality that may cause the UV rays to be diverted to damaging angles.

Reflective surfaces may be fun and stimulating enrichment but should only be used for a limited time and not a permanent part of the enclosure.

4. Correct Photoperiod

Try to replicate the day/night cycle your bearded dragon would experience if it was roaming free in the desert. Create a daily and seasonal schedule and set your lamps to timers.

It doesn’t matter if your bulb goes out for a few days, or you want to switch it off for 1-2 days, the sun does not shine every single day even in the Australian desert so your beardie can handle this. 

This may be beneficial particularly if you suspect UVB overexposure.

Recommended Reading: The 9 Best Timers For Bearded Dragons

How Many Watts Of UVB Does a Bearded Dragon Need?

To ensure you are creating the correct environment and to avoid overexposure to UVB, you need to know how much UVB your bearded dragon needs.

so, how many watts of UVB do bearded dragons need? The wattage of your UV lamp does not matter as much as the placement of the lamp does. If your wattage is high, you would want the lamp further away. If the wattage is lower, bring the lamp down.

You should measure the UVI (ultraviolet index) throughout the enclosure and aim for between 4-6 at the basking spot. 

You do not want the index over 7.4 or below 3 as you may risk under or overexposure.

The wattage of the lamp, the placement and whether or not the bulb has a reflective hood will all influence the UVI in the enclosure. 

When choosing a lamp wattage, choose one that will fit nicely into the enclosure setup you have.

An important note is that UVB bulbs will fade over time. They may emit the same light but the UV output reduces. 

It’s recommended to change UVB bulbs every 6 months to keep output at optimal levels. Your UV reader will come in handy here to monitor bulb output. 

How Many Hours Of UVB Does a Bearded Dragon Need Per Day?

UVB light should replicate natural levels. Light and UVB periods will allow your bearded dragon to stay in natural cycles and allow for natural feeding, resting and reproduction.

So, how many hours of UVB do bearded dragons need per day? In warm months your bearded dragon needs 10-12 hours of UVB. In cooler months they need 8 to 10 hours. Adjusting the time of UVB exposure throughout the year allows for the regulation of seasons and promotes a natural environment for your bearded dragon.

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