It is tempting to soften an old bearded dragon's whole enclosure along with his lifestyle — gentler light, gentler heat, everything turned down a notch. Resist it. Digestion, immune function and appetite in a bearded dragon are all run by body temperature, and a senior who spends his day resting needs reliable access to proper basking heat more, not less, than the youngster who used to patrol his tank. What changes with age is not the need but the delivery: he will not climb or commute for his warmth, so the warmth has to be arranged around his resting life.
The basking spot itself: warm, but not fierce
Aim for a basking surface around 100–105°F (roughly 38–40°C) — the calmer end of the usual adult basking range. A fit adult handles the hotter end happily, but an old dragon is slower to move away when he has had enough and slower to notice he is overheating, so the fierce extremes are less forgiving. At 100–105°F he can still raise his body temperature properly after meals, which is when warmth matters most: an under-warmed senior digests slowly, eats less in response, and slides into the appetite fade owners wrongly blame on age alone.
The gradient does the real work for a resting dragon
A single hot spot over an otherwise cool tank fails a dragon who barely moves. Build the enclosure as a slope of warmth: basking spot at the top end, ambient warm side in the high 80s°F, and a cool end around 80°F where he can genuinely shed heat. Then his whole day of resting becomes micro-adjustment — a few inches toward the lamp after breakfast, a drift toward the cool end by afternoon — instead of an expedition. Measure with a digital thermometer probe or temperature gun at the exact places he lies; the reading on a dial stuck to the back glass is not his temperature.
Make the warm spot effortless to reach
Senior dragons are often stiff, grippy less surely, and unwilling to scale the tall basking towers young dragons love. Bring the basking platform down to a low, wide, gently ramped surface he can walk onto, stable enough not to wobble, with a texture his claws can hold. If his favoured resting place is clearly not the basking spot, do not fight him — move a second, slightly weaker heat source over where he actually spends his day, because a warm-enough spot he uses beats a perfect one he avoids.
Recheck on a rhythm, because bulbs lie
Heat output fades as bulbs age, and room temperature swings with the seasons shift the whole gradient, so a setup that was right in spring can underheat by winter. Recheck basking and cool-end temperatures whenever a bulb changes and at each season change, and watch the dragon as your second thermometer: gaping constantly at the basking spot suggests too hot, while a dragon who never leaves it and still eats sluggishly is often telling you the warm-up is not enough.
Keeping dated temperature readings in his KinsLe Pet Passport — basking spot, warm side, cool end, and which bulb is fitted — means drift gets caught at a glance and a vet asking about his setup gets figures, not impressions.