Bearded Dragon Lighting Guide: UVB, UVA, Heat Lamps, and Photoperiod Basics

UVB light in the roughly 290-320 nm range is essential for reptiles that depend on skin production of vitamin D3. In bearded dragons, that process supports calcium balance and helps lower the risk of nutritional secondary hyperparathyroidism, often called metabolic bone disease. Merck and VCA both note that inadequate UV exposure is a major husbandry problem in pet reptiles.

UVB only helps if it actually reaches your dragon. Glass and plastic can block useful ultraviolet light, and output drops as distance increases. That means a bulb that looks bright to you may still provide too little usable UVB at the basking site if it is mounted too high or screened off too heavily.

UVA is different from UVB. It does not drive vitamin D3 production, but it supports normal reptile behavior, including activity, feeding interest, and day-night signaling. Many reptile bulbs provide both UVA and UVB, but the exact output varies by product.

For pet parents, the practical takeaway is that visible brightness, UVA, UVB, and heat each play different roles. A warm tank that lacks effective UVB is still incomplete, and a UVB bulb without a proper basking zone is also incomplete.

For most indoor bearded dragon setups, a linear fluorescent UVB tube is the most reliable starting point. It spreads light across a wider area than small compact or coil bulbs, making it easier to create a usable basking zone with consistent exposure. Many reptile clinicians and husbandry guides favor a separate basking lamp plus a separate linear UVB fixture for this reason.

A practical target is to have the UVB fixture cover about one-half to two-thirds of the enclosure length, with the basking area overlapping that zone. This encourages your dragon to receive heat and UVB at the same time, which matches natural basking behavior.

Distance depends on bulb strength, fixture design, reflector quality, and whether the bulb sits above mesh or inside the enclosure. VCA notes that many UV bulbs need to be within about 6-18 inches to provide benefit, while some reptile care articles recommend about 10-12 inches for effective exposure in certain setups. Because output falls quickly with distance, guessing is risky.

The safest plan is to follow the bulb manufacturer's distance chart and then confirm the setup with your vet. If your dragon can get too close, overexposure and eye irritation may become concerns. If the bulb is too far away, your dragon may not get enough UVB even though the enclosure looks well lit.

Heat lamps are not interchangeable with UVB bulbs. Their job is to create a basking area warm enough for normal digestion, movement, and thermoregulation. Merck lists basking lights in the 50-75 watt range at least 18 inches from the basking area as a general reptile housing reference, but the correct wattage for a bearded dragon depends on enclosure size, room temperature, fixture height, and ventilation.

Instead of choosing wattage first, choose the basking surface temperature your vet recommends and measure it with a digital probe thermometer or infrared temperature gun. Your dragon should also have a cooler side so it can move away from heat when needed.

Photoperiod means the number of light hours in a 24-hour period. Merck notes that subtropical and tropical reptiles often do well with about 10 hours of light in winter and up to 14 hours in summer. In home care, many pet parents use a steady 12-14 hours of daytime light and 10-12 hours of darkness for bearded dragons, adjusting modestly with season if advised by your vet.

At night, lights should go off so your dragon can rest and experience a normal temperature drop. VCA specifically notes that bearded dragons need a nighttime environment in which temperature drops when the light goes off. Avoid colored night bulbs for routine use unless your vet has a specific reason to recommend one.

UVB bulbs lose useful output over time, even if they still turn on. VCA advises replacing many UV bulbs every 6 months or according to the manufacturer, while Merck notes that some UVB bulbs may be replaced yearly and that measuring output with a UV meter is even better. The difference reflects real variation among products.

For pet parents, the practical approach is to label each bulb with the install date, follow the manufacturer's replacement interval, and ask your vet whether your setup would benefit from periodic UV meter checks. A glowing bulb is not proof that UVB output is still adequate.

Common problems include using a UVB bulb that is too weak, placing it too far from the basking site, letting glass or plastic block the rays, using only a heat bulb without UVB, and forgetting to replace aging bulbs. Another frequent issue is separating the heat source and UVB source so far apart that the dragon has to choose one or the other.

If your bearded dragon seems less active, has a weak appetite, spends all day hiding, or shows signs of tremors, jaw softness, limb swelling, or trouble climbing, ask your vet to review husbandry right away. Lighting is not the only cause of these signs, but it is an important one to check.

A basic indoor lighting setup for one bearded dragon often includes a linear UVB fixture and bulb, a basking dome or fixture, a heat bulb, and timers. In the U.S. in 2025-2026, many pet parents spend about $90-$220 for an initial lighting setup, depending on enclosure size and brand choices. Ongoing bulb replacement commonly adds about $25-$80 every 6-12 months for UVB and about $10-$30 as needed for basking bulbs.

If budget is tight, ask your vet which parts of the setup are essential to replace first. In most cases, maintaining effective UVB and a safe basking zone matters more than decorative accessories.