Bearded Dragon Lighting & UVB Guide

Bearded dragons need UVB to synthesize vitamin D3 and absorb calcium. Without adequate UVB (or correct supplementation when UVB is absent), they develop metabolic bone disease (MBD)—weak bones, deformities, fractures, and often death. UVB is a core part of husbandry, not optional. For the full picture, see our Care Guide and Tank Setup Guide.

Pet-store and starter-kit setups often get lighting wrong. Coil or compact UVB gives a small, uneven patch; the basking area often receives too little, and output drops over time (MBD risk). Skipping UVB and relying only on calcium with D3 is fragile—over- or under-dosing and missed feedings are common. Glass and fine mesh block most UVB; the bulb must be inside the enclosure or over wide-open mesh so the dragon can sit within the recommended distance. Red or blue “night” bulbs disrupt day/night cycles; use a ceramic heat emitter for nighttime heat if needed. Unregulated heat lamps can exceed 120°F+ at the basking spot—thermostats are mandatory. Measure surface temperature at the basking spot (100–108°F) with a temp gun, not just air temp. More pitfalls: Common Bearded Dragon Mistakes.

A T5 high-output linear tube in 10.0 or 12% (some brands use 14%) is the recommended UVB source. Run it along roughly half the enclosure length so there is a clear basking zone and a cooler area without UVB. Mount the fixture inside the enclosure or just above wide mesh—fine screen blocks a large share of UVB. Follow the manufacturer’s distance chart (often 12–18 in for T5 10.0/12%). Replace the tube on schedule (usually every 6–12 months); output declines even when the bulb still lights.

The basking lamp must deliver 100–108°F on the surface where the dragon sits. A halogen flood or incandescent provides both heat and visible light; wattage depends on enclosure size and basking height (often 75–150 W for a 4×2×2). A ceramic heat emitter (CHE) gives heat only—use for night heat or to separate heat from light. Do not use red or blue bulbs for daytime heat. LED strips add brightness but do not replace UVB or basking heat.

Bearded dragons thermoregulate by resting on a hot surface, so the critical number is surface temperature at the basking spot, not air temp. Use an infrared temp gun aimed where the dragon sits; cool-side air can be read with a digital thermometer (mid-70s to low 80s °F). Plug the heat lamp into a thermostat and set it so the surface stays in range; recheck with the temp gun regularly.

Dense screen tops filter out much of the UVB. Mount the T5 inside the enclosure (safely secured) or use very open mesh and place the fixture so effective UVB at basking height meets the manufacturer’s recommendation. Adjust basking bulb height and wattage so the surface under the lamp reaches 100–108°F.