Lighting & UVB
Bearded dragons are diurnal, which means that they are active during the day. And they LOVE the sun. In fact, their parietal (third) eye uses bright light to set the dragon’s circadian rhythm and activity patterns. In other words:
- They must have strong, reliable UVB lighting
- Plenty of bright, white light is needed for energy, appetite, and mental health.
Linear Fluorescent UVB
The following UVB bulbs are appropriate for use with bearded dragons. Pay attention to the recommended basking distances and adjustments for mesh obstruction, as UVB output/strength varies with distances and whether it’s partially blocked by mesh.
- Arcadia T5 HO Desert 12% / Zoo Med T5 HO Reptisun 10.0
- mesh: 9-11″ /23-27cm
- no mesh: 14-17″ / 35-42cm
- Arcadia T5 HO Dragon 14%
- mesh: 10-12″ /25-30cm
- no mesh: 14-18″ / 35-45cm
(These recommendations are an approximation based on the assumption of a ~45% mesh block. For more details on adjusting basking distance based on mesh obstruction, see the Facebook group Reptile Lighting > Guides > Guide 1: Using T5-HO lamps above a Mesh Screen.)
Extra distancing advice: If you don’t have a Solarmeter 6.5 on hand, I strongly advise adding 1-3″ to the recommended distance to account for your specific dragon’s height. The basking area should be the highest point in the enclosure, and closest to the UVB bulb.
How long should the bulb be? For maximum effectiveness and safety, the bulb should be roughly 1/2 the length of your enclosure and placed on the same side as your heat lamps. For a 4′ enclosure, that means you will need a 22″ UVB bulb. For a 6′ enclosure, you will need a 34″ UVB bulb.
Make sure that your fixture does not have a piece of glass or plastic to “protect” the bulb. UVB rays are blocked by glass and plastic, rendering that bulb you just spent so much money on completely useless. Naked UVB bulbs are effective UVB bulbs! Don’t believe me? Just read this case from The Reptile Doctor.
UVB Replacement Schedule
- Mercury vapor bulbs — every 6-12 months, depending on manufacturer
- T8 fluorescent — every 6 months
- T5 fluorescent — every 12 months
For more accurate monitoring of your bulb’s UVB output, I recommend investing in a Solarmeter 6.5. This will help you keep track of the UVI (UV index) within your beardie’s enclosure, and whether it is actually getting too much or too little exposure. According to experts, the optimal UVI gradient for a bearded dragon is 0 to 4.0-6.0, from lowest (furthest from the bulb) to highest (basking area). Most normally pigmented bearded dragons can tolerate UVI of up to 7.0 safely, but these levels are not necessary in captivity for optimal health. For a visualization of the optimal gradient, refer to Arcadia’s Lighting Guide for Full Sun Baskers.
NOTE — Certain morphs of bearded dragon with reduced pigmentation (hypomelanistic, albino, translucent) or thin scales (leatherback, silkback) are likely to be more sensitive to high quantities of UVB. They may need a lower-strength UVB bulb, and should be exposed to UVI of no more than 3.0 in the basking area. Bulbs for these morphs should also span only 1/2 of the length of the enclosure, instead of 2/3.
Full-Spectrum Daylight Lighting
Bearded dragons are known as “sun worshippers” — they are incredibly dependent on having plenty of bright white light in their enclosure. This helps promote activity, appetite, and general wellbeing.
In addition to halogen heating and UVB, your bearded dragon also needs bright ~6500K illumination in order to enjoy optimal wellbeing. Aside from making a big difference in your dragon’s health and activity, it also boosts the attractiveness of your setup.
ReptiFiles recommends the following lamps for brightening a bearded dragon enclosure. These lamps should cover 75-100% the length of your enclosure, which means that you may need multiple lamps to do the job.
- Arcadia JungleDawn LED Bar
- Bio Dude Glow & Grow LED
- Vivarium Electronics T5 HO Dual Bulb Light Strip, 36″ (NOT for use with UVB bulbs!)
Like all reptiles, bearded dragons need heat to digest and maintain their immune systems. Without it, they get sick and die. Since bearded dragons are basking lizards, they use heat most effectively from an overhead heat source that mimics the sun.
Since they are cold-blooded, bearded dragons need a temperature gradient in their enclosure in order to be able to regulate their body temperature. Although they can tolerate very high basking temperatures, they need to be able to escape to cooler areas in the enclosure to prevent overheating. For example, if we were looking at an average enclosure from left to right, the highest temperatures should be at the far left, gradually descending to the lowest temperatures on the far right.
- Basking side surface temperature— 108-113°F (42-45°C)
- Cool side surface temperature — 77-85°F (25-29°C)
- Air temperature gradient — 72-99°F (22-37°C)
- Nighttime — 55-75°F (12-24°C)
The recommended basking surface temperature shown above is based on recommendations in Judish Badham’s 1971 PhD thesis, A comparison of two variants of the bearded dragon, Amphibolurus barbatus (Cuvier) (since then verified by Dr. Jonathan Howard), where rectal temperatures of P. vitticeps were taken when the dragons moved away from the sun, showing that they were done basking for the moment, and presumably having reached optimal temperature. Their findings indicated that the optimum core body temperature of central bearded dragons is 36.3°C (97.3°F), which requires basking site temperatures between 42-45°C (108-113°F) to achieve. Dr. Howard’s basking substrate surface temperature measurements suggest that the basking surface in a bearded dragon enclosure does not need to exceed 50°C (122°F), as this risks overheating the enclosure.
What should you use for a basking surface?
Surfaces like rocks and logs tend to collect heat over the course of the day, becoming significantly warmer than the surrounding air (for example — have you ever burned yourself on a seat belt buckle even though the air in your car wasn’t that hot?). According to a study by Jane Melville and James Schulte, active body temperatures in Central Australian agamid lizards correlate closely with surface temperatures, which means that measuring basking surface temperature is very important (more on how to measure surface temperature later). For these reasons, a stone basking surface should be provided, as this material is best at absorbing heat for bearded dragons to use. That said, sturdy basking branches also perform well.
Is it safe for a bearded dragon to have low nighttime temperatures?
Most reptiles benefit from a nightly drop in temperature, which science suggests may promote a healthy metabolism and even strengthen the immune system (rather than weaken it, as commonly believed). Provided that daytime temperatures are correct, pet bearded dragons can handle nighttime drops as low as 50°F without ill effect. In fact, providing cooler temperatures at night encourages beardies to bask in the morning, which subsequently makes for a more active dragon. However, without adequate daytime warming, these cool temperatures may induce brumation or illness.
Best Heat Bulbs for Bearded Dragons
Use a high-wattage halogen bulb inside of a dome heat lamp with a ceramic socket to safely achieve the right basking temperatures and thermal gradient. ReptiFiles recommends using a cluster of at least 2 halogen flood bulbs to provide high-quality Infrared A and B radiation to help your pet thermoregulate most efficiently. I recommend the following bulbs:
- Reptile Systems Infrared Gold Unit, 200w
- Zoo Med Repti Tuff Splashproof Halogen Lamp
- Arcadia Halogen Heat Lamp
Wattage = heat output. Whether you’re using a 4’x2’x4′ or 6’x2’x2′ enclosure, 90-100w should achieve the temperatures you need. If you need hotter, raise the basking surface (preferably stone rather than plastic, mesh, or fabric) closer to the heat source. If you need it to be a bit cooler (basking surface temperature over 120°F is too high), use a lamp dimmer like the Vivarium Electronics Rheostat to reduce heat output, but don’t dim the bulb too much, or else you start to lose valuable IR-A.
- Note: The Reptile Systems infrared unit is an exception. This is a GREAT heat lamp due to its sky-high Infrared-A output, but it’s different from what you’re used to. You only need one unit due to its wide spread, and don’t be alarmed by the deep red color — it’s not the same as a typical “red bulb.” Charts for approximate basking temperature at varying distances are available on the manufacturer’s website here.
Ambient Heating for Bearded Dragons
When setting up a large reptile enclosure, chances are good that basking bulbs alone won’t be enough to create the temperature gradient that your pet needs. If this is the case for your enclosure, you will need to add secondary heat sources to boost your ambient temps.
It’s best to use lightless heating for this purpose, such as:
- Sweeter Heater Radiant Heat Panel
- Arcadia Deep Heat Projector
- Zoo Med ReptiCare Infrared Heat Projector
- Ceramic heat emitter
Use whatever wattage works best to maintain appropriate minimum ambient temperatures — although generally speaking, this means you should be looking at the lowest-wattage options. Depending on the size of your enclosure, you will need 1-2 ambient heaters.
For enclosures taller than 3′, you may need to get handy and install your ambient heating under a ledge about halfway down the enclosure to make sure the cool zone isn’t prohibitively cold during the day. Radiant heat panels work particularly well for this purpose, as they are built specifically to prevent contact burns.
Heat panels and heat projectors should be controlled via rheostat or dimming (proportional) thermostat. Because they produce IR-B and IR-C, you don’t have to worry about negative effects from dimming too much. Ceramic heat emitters are less sensitive and can be controlled via rheostat or on/off (non-proportional) thermostat.
Having trouble with short-lived bulbs?
- Wash your hands thoroughly with soap before installing the bulb. Skin oils can potentially reduce heat bulb’s lifespan.
- Check your heat lamp. Is it rated for the wattage of the bulb(s) you’re using? Does it have a ceramic socket? If not, that’s likely your problem, as well a fire hazard.
- Make sure the lamp is plugged into a surge protector. These bulbs are sensitive to fluctuations in electrical supply, making them more likely to burn out prematurely. A surge protector does what the name implies — protects your bulb from surges.
- Ask yourself: Has the lamp taken a fall recently? The filaments in these bulbs are fragile, likely the result of needing to produce UVA. Jostling or falling while the bulb is hot can prematurely break the filament.
- Contact the manufacturer. If you have done everything correctly, it’s likely that you just got a bad bulb. Check the bulb’s warranty, and if it’s still covered, get in touch with the manufacturer to get it replaced free of charge. For example, the Zoo Med Repti Basking Spot has a 3-month warranty!
How do you make sure you’re doing it right?
First, you need to make sure that you’re getting the right surface temperatures. To measure this, you will need an infrared temperature gun. I got an Etekcity Lasergrip 774 off Amazon, and it’s spectacular.
While using your temp gun, make sure that the basking temperatures cover an area at least as large as the dragon’s entire body (including tail), as hot spots can be dangerous. And don’t take temperature readings until the heat source has been going for about 3 hours, as earlier or later will give you an inaccurate reading.
Second, you need to make sure that your air temperatures are high enough. A warm basking surface is no good if the air is too cold, and too high air temperatures can give your dragon heat stroke. Keep track of the air temperature in the basking area with a probe digital thermometer like the Zoo Med Digital Combo Thermometer and Humidity Gauge, which is inexpensive and I have been quite pleased with in my own use.
You need both a temp gun and digital thermometer to get a complete and accurate picture of your bearded dragon’s thermal gradient. One should not be used without the other!
Every living creature needs water, even the ones that live in arid desert environments. Water is available in three main ways:
Although it’s good practice to keep a shallow water dish in your bearded dragon’s enclosure, bearded dragons get most of their water from their food and from the air that they breathe. Yes, you read that correctly — they can get water from the air. Granted, it’s not very much water. But this small amount of water from ambient humidity helps keep their lungs, skin, and scales healthy.
A common misconception about bearded dragon husbandry is that humidity should be as low as possible, and any instances of relatively high humidity put the dragon in immediate danger of illness. People who perpetuate this myth forget that Central Australia is not bone dry, and it does rain, and humidity does rise occasionally. It’s also important to note that the average human home significantly drier than outdoors, and sometimes too dry, especially if you live in an area with a naturally dry climate. (Fun fact: the ideal indoor humidity for humans is 40-45%.)
The ambient humidity in your bearded dragon’s enclosure should average between 30-60%. You can measure this using the abovementioned Zoo Med Digital Combo Thermometer and Humidity Gauge, with the humidity probe placed on the cool end of the enclosure. Lower or higher than that, and your beardie may start to develop respiratory problems. It may also cause problems with the skin and scales, especially if the substrate is frequently wet. However, occasional brief spikes in humidity due to watering plants in the enclosure, rainy weather, or nighttime is perfectly natural and safe.
Heat and humidity have an inverse relationship. Where it’s hot (such as your basking area), humidity will be low — potentially as low as 10%. Where it’s cool, humidity will be higher. This gradient of temperatures and humidity, as long as they are within correct parameters, will be beneficial, not harmful.