Bearded dragon brumation lighting hours

Bad lighting is the single most common husbandry mistake with bearded dragons — incorrect UVB output or basking temperatures cause metabolic bone disease and chronic illness that many owners don't notice until real damage has already been done. Your situation is a bit different though: a four-year-old dragon showing brumation signs needs a careful lighting adjustment, not a switch-off. Before I walk you through what to do, a few quick questions — what size is the enclosure, what UVB and basking bulbs are you currently running (brand and wattage), and has a vet confirmed this is brumation rather than illness?

Good — that setup is solid, and a clean bill of health two months ago with classic brumation signs in autumn is exactly the picture you want to see. Here's what to do with lighting during brumation: don't switch everything off, but do follow his lead. Drop the photoperiod gradually — move from your current schedule down to around 8 hours of light per day over two to three weeks. Keep the UVB running during those hours because even a brumating dragon benefits from some exposure, and a T5 6% in a 4x2x2 is appropriate. Reduce the basking spot temperature slightly — aim for around 95°F rather than the usual 105–110°F — so he's not being driven to thermoregulate when his body wants to slow down. If he stops coming out entirely, you can drop to 6 hours. The key rule: always offer light and heat during the hours you do run the lights, so he has the option. Never leave him in total darkness for weeks.

The Arcadia T5 6% is exactly right for a 4x2x2 and stays correct through brumation — you don't need to change the tube. What I would check is the age of the bulb. Arcadia recommend replacing T5 UVB tubes every 12 months even if they still appear to glow, because UV output degrades significantly before the visible light fails. If your current tube is over 9–10 months old, replace it now before brumation so you're not running degraded UVB into spring when he comes out and needs full output to rebuild. The product I'd point you to is the Arcadia T5 HO 6% UVB Lamp — the 39W size to match your existing controller. It's the most reliable T5 tube available for bearded dragons in the UK and fits your current fitting without any additional outlay.

Replace it now. At 8 months the UV output will have dropped noticeably from the rated output, and going into brumation with a degrading tube means he'll emerge in spring into continued sub-optimal UVB right when his metabolism is ramping back up and he needs it most. A fresh Arcadia T5 HO 6% 39W tube fitted now means you'll have full-strength UVB through the reduced brumation hours and solid output for the full 12–14 hour days when he wakes up. It's a small cost against the risk of compromised UVB at a critical transition point. Mark the fitting date on the tube with a permanent marker so you know when to replace it next year.

He'll tell you. As days lengthen in late winter or early spring, you'll see him becoming more alert, basking more actively, and eventually showing interest in food again. When that starts, begin extending photoperiod by around 30 minutes every few days back toward 12–14 hours, and bring the basking spot back up to 105–110°F. Don't force feed the moment he stirs — let him bask and thermoregulate for a few days first, then offer food when he's clearly active. The whole ramp-up usually takes two to three weeks. If he hasn't stirred by late March and ambient temperatures have warmed, you can start increasing light hours proactively to encourage him. You're clearly on top of this — a healthy four-year-old with a vet check and good equipment going into his first brumation is in a great position.