We get many questions surrounding UVB and bearded dragons. For this reason, we have taken the 18 most commonly asked UVB questions that we get and answered them in one convenient post.

We have added a clickable table of contents so you can jump to the question you want to see the answer for.

The article should help you understand the role UVB plays in your bearded dragon’s growth and overall health and should allow you to care for your bearded dragon in a much more confident way.

Ok, Let’s start answering the 18 frequently asked bearded dragon UVB questions that you simply must know…

Bearded Dragon UVB – 18 Frequently Asked Questions

Do Bearded Dragons Need UVB?

Bearded Dragons need UVB as it is vital for the synthesis of vitamin D3. Vitamin D3 is essential for the absorption of calcium from the diet. A lack of UVB can result in serious health issues such as metabolic bone disease.

UVB is the catalyst for a long and complicated chain of chemical reactions in Bearded Dragons. UVB turns pro vitamin D (in reptile skin) into pre-vitamin D. 

Warmth then converts pre-vitamin D into vitamin D3, which is used in the liver to create a hormone called calcidiol. 

Calcidiol assists in calcium metabolism and also is proven to lower the risk of cancers in Bearded Dragons.

Check out this easy-to-follow guide that covers if bearded dragons actually need calcium powder…

Simply said, UVB is essential for calcium absorption and general health!

Lack of calcium is a key contributor to metabolic bone disease, inadequate growth and development, and reproductive illnesses. These issues can be painful and ultimately fatal for a Bearded Dragon if not managed correctly.

Providing UVB, in conjunction with correct temperatures and diet, will contribute to promoting healthy metabolism and a hormone balance in your Bearded Dragon.

Do Bearded Dragons Need UVB at Night?

Bearded Dragons do not need UVB at night. UVB is only required during natural daylight hours as wild Bearded Dragons will gather UV from the sun. Leaving the UV light on during the night can cause overexposure to UV and disrupted sleep.

Your pet Bearded Dragon only needs a UV light as they can’t make the most of the sun all day like its wild counterpart in the Australian desert.

The sun does not shine around the clock naturally, so neither should your tank UV light. You should be providing UV only during daylight hours and turn it off through the night. 

The below table outlines the hours needed across the seasons.

Bearded Dragon Hours Of Heat & Light Required Daily

SeasonHours Of Heat & Light (Per Day)

These day/night cycles are called photoperiods and your beardie takes cues from these environmental changes as when to be active and when to rest. 

Maintaining a natural photoperiod promotes restful sleep and active days. 

UV lights are generally light-emitting so it is also important they are off during the night. Bearded Dragons need darkness to sleep. 

Just like us, sleep is supported by an increase of melatonin in the brain which is synthesized by dark environments.

An excess of light through the night can cause sleep deprivation and contribute to a multitude of health problems.

Here’s our new guide that shares the 10 reasons why bearded dragons can find it hard to sleep…

Do Bearded Dragons Need Both UVA and UVB?

In addition to UVB, your Bearded Dragon needs UVA wavelengths also. UVA light is a factor in regulating natural behaviors such as feeding, reproduction, and movement. UVA also supports healthy social behaviors and interactions.

UVA is the wavelength that signals it is daytime to beardies brains and will promote activity including feeding, basking, socializing, reproduction, and investigating.

“UV” means ultraviolet as this spectrum has greater energy than we humans can see. The wavelengths we see are violet light.

Many animals, including Bearded Dragons, can see UV light and it is vital for their behaviors. 

Bearded Dragons recognize each other by marking and colors, which are more complex than what we can see, and much of it is reflected in UVA color. 

Thus, UVA is essential to supporting these social interactions (including interspecies socialization – with us!) as it is how your beardie will take cues on body language and communication. These behaviors signal a happy and normal beardie.

Difference Between UVA and UVB For Bearded Dragons?

Bearded Dragons need both UVA and UVB. There are differences between the benefits of these UV wavelengths. UVA promotes natural cycles and behaviors and supports the behavioral side. UVB is the catalyst for vitamin D3 synthesis and calcium absorption and supports physical health.

UVA regulates all behaviors of your Bearded Dragon as it is the key to signaling day vs night in the brain. 

UVA wavelengths let your beardie know it is daytime and encourage feeding, basking, and socialization.

UVB is the vital ingredient for calcium absorption from the diet and supports the growth, development, and repair of cells.

See the table below for a comparison of UVA and UVB effects.

Health Benefits Of UVA & UVB For Bearded Dragons

Natural photoperiodVitamin D3 synthesis
Feeding behaviorsCalcium absorption
Basking behaviorHealthy growth and development
Social interactions & reproductionEfficient metabolism

The other wavelength of UV is UVC. UVC light is not required for reptiles but it can help control bacteria in the environment. 

High levels can be harmful so if uncertain it’s best to emit UVC light from your Bearded Dragons enclosure.

How Many Hours A Day Do Bearded Dragons Need UVB?

Bearded Dragons should be provided with UVB during natural daylight hours to emulate the most natural environment. They should have access to UVB from 10-14 hours a day. This will depend on the season, during winter they will need less (10 hours) and during summer they will need more (14 hours).

The hours of UVB required for Bearded Dragons changes through the year. You should aim to create a sense of seasonality for your beardie as this can support healthy behaviors, particularly regarding reproduction.

In summer, the days are longer due to the tilt of the earth and the exposure to the sun. You can reproduce this in your Bearded Dragons enclosure by providing approximately 14 hours of UV and light.

In wintertime, this amount of UV can go down to around 10 hours. Autumn and Spring should be somewhere in the middle at 12 hours of UV exposure.

Your Bearded Dragons seasonal cycle is most easily managed by matching it to the seasons in which you live. Use a timer, which you alter seasonally, to manage your UV bulbs to ensure consistency.

Bearded Dragon Hours Of Heat & Light Required Daily

SeasonHours Of Heat & Light (Per Day)

Can A Bearded Dragon Have Too Much UVB?

Bearded Dragons can have too much UVB. Bearded Dragons will self-regulate and seek UVB as required but overexposure can occur when they cannot get away from UVB rays. Overexposure to UVB can result in a range of issues such as hypercalcemia, photo-kerato-conjunctivitis, or hyperkeratosis.

When provided with the correct environment Bearded Dragons will take care of themselves. They will adjust their behaviors according to their needs, including seeking UVB rays as required to stay healthy.

If your enclosure is poorly set up it may lead to your beardie being not able to escape from UV rays in the tank. 

UV dissipates as it moves through the air, so placing your UV lamp on one side of the enclosure will mean the opposite side has the lowest exposure to UV and your beardie can utilize this area to get away from UV.

Provide plenty of hides for your Bearded Dragon so they can be shaded from the UV when they feel like it.

Too much UVB can lead to:

  • Hypercalcemia – a build-up of calcium can lead to calcium deposits throughout the body, oftentimes the kidneys can bear the brunt of this and become mineralized and result in secondary renal hyperparathyroidism.

  • Photo-kerato-conjunctivitis – this basically is sunburn for the eyes! This painful affliction can cause irreversible damage to the eyes and vision.

  • Hyperkeratosis – this is the chemical thickening of the skin in response to stressful stimuli (in this instance, excess UVB). This can cause painful calluses and restrict movement but in dire cases, it can cause thickening around the nose and mouth restricting eating or breathing.

Head over to our new article that covers in detail the signs, causes, and solutions of too much UVB exposure for bearded dragons…

How To Tell If My Bearded Dragon Isn’t Getting Enough UVB

You can be sure your Bearded Dragon is getting enough UVB by measuring the UVB rays in the basking spot with a UV reader and recording the time it spends basking here. Lack of UVB can cause metabolic bone disease, symptoms of which include: dragging legs, paralysis, muscle wastage, and deformities.

It can be hard to know for sure if your Bearded Dragon is getting enough UVB and the signs that it is not receiving enough UVB may not be so obvious until things are already dire.

To ease your mind you should invest in a UV reader such as a solar meter that will record the UV index in your beardies enclosure. 

Check Out This Solarmeter We Recommend Solarmeter On Amazon…

Solarmeter Model 6.5R Reptile UV Index Meter, Handheld Digital Radiometer for Measuring Ultraviolet Light, Measures 280-400 nm with Range from 0-199.9 UV Index, Made in USA, ABS Polymer, Black
  • Total UV Meter - Make sure your UV lamps are up to manufacturers' standards with this practical light meter, perfect for monitoring PUVA therapy lamp...
  • Change Your Lamp Bulbs on Time - Special purpose bulbs decay over time and stop emitting the amount of UV light they should; with our Solarmeter,...

Last update on 2023-12-10 / Affiliate links / Images from Amazon Product Advertising API

Take readings from the basking spot your Bearded Dragon spends most of its time. 

If the index is within range (2.5 – 4 nm – perhaps up to 7nm) and your beardie spends a significant amount of time basking, then you can be assured that it is getting adequate UVB.

Take UV readings monthly to monitor that the lamp is holding quality. When it starts to reduce in effectiveness, replace it.

If your Bearded Dragon does not get enough UVB and develops MBD the signs may be subtle but include:

  • Muscle weakness
  • Dragging back legs
  • Paralysis
  • Physical deformation e.g lumps or bends on spine, tail or joints
  • Muscle twitching
  • Fragile bones
  • Soft jawbones

How Long Can Bearded Dragons Go Without UVB?

Bearded Dragons should have access to UVB daily. Adults can potentially go for up to a week without UVB before their health suffers greatly. But minimizing this time is vital, anything more than 2 days will pose a risk.

Bearded Dragons need UVB to synthesis vitamin D3 and absorb calcium properly. Without UVB they will be at risk of developing a whole host of illnesses.

Extended periods without UVB can cause irreversible damage to the health and condition of your Bearded Dragon and eventually will be fatal.

Sometimes loss of UV is beyond our control such as blown lamps or power cuts. You should aim to always have a spare UV bulb or two in the case of a blown lamp so you can replace it immediately and not have any loss of UVB.

In the case of an extended power cut, you can attempt to use the sun to provide your beardie with vital UV rays. 

UVB does not penetrate glass so placing a glass tank in the sun will not work, your Bearded Dragon will need direct exposure.

You can also invest in a flashlight that has a UV bulb for these kinds of emergencies.

Recommended Reading: Why Bearded Dragons Need Calcium

How Long Can A Baby Bearded Dragon Go Without UVB?

Baby Bearded Dragons grow and change at rapid rates and need UVB to sustain this development. They should have UVB provided daily. The longest they should go without UVB is a couple of days. Any more and permanent health issues can develop or growth is stunted.

Metabolic bone disease is much more common in young Bearded Dragons than it is in adults. This is due to the rapid and aggressive growth and development that babies are constantly undergoing for the first stages of their lives.

Their rapid growth is supported by large appetites, high activity, lots of basking, and vital UVB intake to assist in calcium absorption and a healthy metabolism.

Calcium is one of the key minerals for bone development and baby beardies have high needs during periods of growth. 

Lack of UVB can limit calcium absorption and in turn, cause growth issues that will likely persist through their adult lives.

Here’s an article complete with tables and charts that detail how fast bearded dragons grow…

Limit anytime UVB is not provided for baby beardies by keeping spare UV bulbs always and battery-powered UV flashlights or lamps in case of emergency.

How Far Should The UVB Bulb Be From My Bearded Dragon?

The distance of your UVB bulb from your Bearded Dragon should be between 4 – 16 inches. This variance depends on your UV lamp’s wattage and the dissipation of UV through the air. The barriers that exist between the lamp and basking spot will also influence this distance.

UVB wavelengths are measured in nanometers (nm). The nm of UVB required for reptiles depends on their needs, this is divided up into “Ferguson Zones”. 

These zones outline basking and UV requirements for various species.

Bearded Dragons sit between zone 3 and 4, but are classified as zone 4 baskers – reptiles that openly bask. 

The range of UVB provided for your beardie should be between 3-7nm, never above 7nm. Between 2.5-4 consistently is ideal.

Use a UV reader to measure UVB readings throughout the enclosure, particularly in the basking spot.

The distance of the UV lamp from your beardie to achieve this perfect UVB index will depend on the output of your lamp (measured in watts). 

See the table below for a general guide:

Bearded Dragon UV Lamp Placement

UV Lamp Output (Watts)Distance required (inches)

It is ideal for your UV lamp to be directly in the enclosure to provide unfiltered UVB rays. Barriers can reduce the effectiveness of the rays. 

Mesh will not allow as many nm of UVB to reach your beardie and glass does not allow any UVB to permeate.

How Many Watts Of UVB Does A Bearded Dragon Need?

Your Bearded Dragons UVB bulb should have a wattage between 80 – 160. The ideal wattage for your enclosure will depend on your set-up, the space available, and where your UV lamp will be placed. Lamps with high wattages will have a higher UVB output and need to be placed further away.

Wattage is a measurement of power in a bulb. With UV bulbs the wattage will directly influence the output of UVB and nm of wavelength that is in the enclosure.

You should aim for 2.5-4nm of UVB on your Bearded Dragons basking spot. This can be up to 7, but never above 7nm.

When choosing the wattage you need to take into account the set-up of your enclosure. The UV lamp is best placed in the enclosure so that no UVB is filtered. 

If your enclosure is limited for space, you may want to opt for a bulb with a lower wattage.

If your enclosure is large and your bulb will be high, a higher wattage will ensure the correct amount of UVB will reach your beardie. 

Higher wattage bulbs should also be chosen if you have to place the bulb outside the enclosure and there are barriers between the bulb and the basking spot such as mesh.

Use a UV reader to test the placement and wattage of bulbs to find the best spot and bulb to suit your set-up. 

How Often Should I Change My Bearded Dragons UVB Bulb?

Bearded Dragon UVB Bulbs will reduce in efficiency as they age and produce less UVB. UV bulbs should be changed every 6 months to a year. Using a UV reader will help pinpoint the correct time to change the bulb. Without a reading, every 6 months will ensure efficiency. 

The output of a UV bulb reduces over time and becomes less effective. The output of a UV bulb is not visible by just looking at it – you can see if it is on or off, not how much UV it is putting out.

How long your UV bulb stays effective depends on the quality of the bulb. Better quality bulbs can last longer, up to a year. 

The box your bulb comes in should advise you of its approximate lifespan.

You should regularly (at least monthly) measure the UV index to monitor the deterioration of the bulb so you know when to replace it. Use a UV reader to take readings. Aim for a UVB index of between 2.5 – 4. 

If you do not have a UV reader, that’s okay! If you purchased a good quality bulb with great reviews you can mostly be assured it is performing as it should. 

Here’s the UVB bulb we recommend you use…

No products found.

In this case, you should replace it every 6 months to maximize efficiency. 

Purchasing a UV reader may save you money in the long run as you may be able to extend the time you keep a UV bulb as you can pinpoint exactly when it needs to be replaced.

Are UVB Bulbs Bad For Bearded Dragons?

UVB bulbs are not bad for Bearded Dragons. In fact for indoor enclosures, UV bulbs are essential to keep your Bearded Dragon healthy. Some bulbs may cause adverse effects if not used correctly. Your enclosure setup can influence the effect of your UV bulb.

UVB bulbs are good for Bearded Dragons as it provides them with vital UVB to support vitamin D3 synthesis and calcium absorption. 

Without a UVB bulb, a Bearded Dragon indoors will not be able to function properly and will deteriorate in health.

Your UV bulb can become bad for your Bearded Dragon if it is placed too close, is too intense or your beardie cannot get away from it.

If your Bearded Dragon is receiving UVB at too high of an index (above 7nm) then it can risk becoming sick from overexposure. 

You can avoid this with a perfect enclosure set up that provides hides, a UV gradient, and the correct temperatures.

Are Coil UVB Bulbs Bad For Bearded Dragons?

Coil UVB bulbs are not ideal for Bearded Dragons. Coil bulbs only provide direct UVB rays and are oftentimes much too strong. Coil bulbs are unreliable and inconsistent and if used incorrectly can be bad for your Bearded Dragon by overexposing them to UVB.

Coil UVB bulbs have got a pretty bad rap in the Bearded Dragon community. 

Many low-quality bulbs cause serious issues by having a UVI (Ultra-violet Index) that is way too high. 

Coil bulbs are also smaller in surface area than tube bulbs and only provide UVB in a pinpointed spot, not through the enclosure.

This direct UVB creates a lack of choice for your beardie when it seeks out UVB. It either gets nothing or way too much.

Many high-quality and new coil bulbs do not have the same issues as historical coils but are still not the best choice for creating a natural and safe environment for your Bearded Dragon.

Should I Use A UVB Bulb or Tube For My Bearded Dragon?

The size of the UVB lamp you use will differ based on your enclosure design. If your enclosure is small, you may opt for a UV bulb that focuses the UVB rays. Most enclosures will benefit best from a tube UVB bulb that provides a wide range of access to UVB so your Bearded Dragon can choose.

Tube lighting is the best choice for most Bearded Dragon enclosures as it covers a wider area so that your Bearded Dragon has more access to UVB across the enclosure, not just when it is basking.

If your UV is focused to one point, then there is a higher risk your Bearded Dragon won’t get enough UV if it doesn’t like that spot. 

Spread out UV rays provide more choice. Tube lighting will let there be a low UV index throughout any open area of the enclosure and then to reach the right index of UVB needed, your beardie can use furniture to get closer and bask under heat and UV.

UV will dissipate through the air so the index will be lower the further from the bulb. The tube should be placed off-center, closer to the basking side of the enclosure.

If you think of it, the sun is so large it covers all of the outdoors in the Bearded Dragons’ natural environment. 

When beardies want to get away from UV they can use shaded areas that block the light and UV. 

This is the role that hides play in your Bearded Dragon enclosure. Providing adequate hides will make sure your beardie can escape the UV when it wishes.

When they want to get more sun and UVB rays, they find a high basking point. You can emulate this with furniture under your lamps.

To increase UVB across the enclosure you can add a reflector to your tube bulb to increase the area the UVB reaches.

Note: do not use household fluorescent tubes. Always use UV bulbs manufactured for reptiles.

Why Isn’t My Bearded Dragon Laying Under the UVB Bulb?

There can be multiple reasons your Bearded Dragon is not laying under the provided UVB bulb. Often this is due to enclosure set-up. For example, the UV bulb may be too close, too intense, or not in the right spot.

Your Bearded Dragon usually needs to sit under the UVB to get the full benefits. Naturally, it can be concerning if they do not sit under the bulb as they may not be getting enough UVB. 

There are a few reasons your beardie may not be under the UV, most are due to enclosure set-up.

Incorrect placement

Your UV bulb needs to be placed above your Bearded Dragon and not coming in from the side of the enclosure.

The eyebrow ridges that Bearded Dragons possess have developed to protect their sensitive eyes from UV rays from above. If the UV is coming in from the side, it may be irritating to the eyes and your beardie does not want to sit near it.

Too intense

Your Bearded Dragon may not want to sit under the UV bulb because the output is too intense. 

The UVI where your beardie sits should be between 2.4 – 4nm and not above 7nm. Anything higher than 7nm is too intense and will deter your Bearded Dragon from this area.

The intensity of the UVI will depend on the wattage of your UVB bulb and the distance from the basking spot. 

Separate from the heat lamp

Your UV bulb should be placed next to the heat lamp so that in the basking spot your Bearded Dragon receives both heat and UVB which work together to help reptiles function. 

In the wild, the sun provides both these things so this should be emulated in your enclosure by keeping these bulbs together.

The heat is most comfortable for your beardie so if your UV bulb is on the opposite side of the enclosure it may not utilize it and this risks a lack of UVB.

Can Bearded Dragons See UVB Rays?

Bearded Dragons can see UVB rays. They have a much better vision than we do. They possess an extra color receptor that helps them to perceive wavelengths, colors, and shades far beyond human capacity. 

Bearded Dragons are tetrachromatic which means that they have four color receptors (we have 3). This extra receptor is responsible for the visualization of UV spectrums.

When it comes to ensuring they get adequate UVB for a healthy metabolism, their vision of UV rays is not that important. Without this, they still instinctively know that bright area will provide them with UVB and dark areas will not. These instincts will regulate their UVB intake.

Instead, the ability to see UV is used by Bearded Dragons for socialization and mate choice. 

Each beardie has different colors and markings and these are much more pronounced when viewed with the visual comprehension of UV wavelengths that beardies possess. 

Bearded Dragons use this to identify friends, foes, and mates and also to locate food.

Recommended Reading: How Bearded Dragons See…

Can Bearded Dragons Get UVB From The Sun?

Yes, Bearded Dragons can get UVB from the sun. The sun is the source of heat and UVB for wild Bearded Dragons and is what powers all of a Bearded Dragon’s behaviors and maintains physical health. 

For your pet Bearded Dragon, you can choose to utilize the sun too if you wish. Adventures outside can be stimulating for beardies and a good chance to soak up some UVB on a sunny day.

You should not substitute the sun for UV lamps in your Bearded Dragons enclosure unless you live in the Australian desert-like wild beardies! In which case an outdoor enclosure with no lamps is fine.

Most people do not keep Bearded Dragons in their natural habitat so need to emulate natural conditions, a UVB lamp is a key component of this.

When utilizing the sun’s UV rays with some outside time make sure you stay with your Bearded Dragon and monitor it constantly.

You can put your Bearded Dragon in an outdoor enclosure for the day if it is lovely and sunny, just do not use a glass enclosure

A glass tank heated by the sun from the outside will get exponentially hotter than a wire enclosure that maintains airflow.

Your glass Bearded Dragon enclosure can get fatally too hot if exposed to the sun. This is the same for keeping an indoor glass enclosure by the window.

Use thermometers and UV readers to ensure the environment your beardie is in (even just for a short while) is within suitable and safe ranges.

Related Posts