A Mediterranean climate in miniature
A Hermann's tortoise is built for rocky Mediterranean slopes: bright mornings, hot midday sun, cool shade and chilly nights. Recreate that pattern rather than a flat warmth. The basking spot, measured at shell height under the lamp, should reach about 90 to 95°F; the air around the warm end sits in the mid 80s; the cool end rests in the low to mid 70s; and at night the whole enclosure is allowed to fall into the 60s. That daily swing is not a flaw in your heating — it is what tells the tortoise's body the time of day and season, and a tortoise kept at one unchanging temperature often slows down and stops eating well.
Heat from above, never from below
Tortoises sense and respond to heat arriving from above, the way sunlight does, and they are poorly equipped to judge heat coming up through the floor. A heat mat under the substrate can leave a tortoise sitting on a hot surface it does not read as dangerous, risking burns to the plastron and overheating the whole animal. All of a Hermann's heat should come from overhead: a basking bulb for the daytime hot spot, and, only if the room falls well below the low 60s at night, a ceramic heat emitter — which gives heat without light — to take the edge off. Both belong on thermostats, the basking lamp on a dimming unit so it glows steadily rather than clicking on and off.
Lamp, thermostat and UVB work as one system
In the wild, heat and ultraviolet arrive together, so place the UVB source over the same end as the basking lamp: the tortoise then warms up and makes use of ultraviolet in the same spot, as it would on a sunny bank. Set the lamp height by measurement, not by eye — raise or lower it until a probe thermometer lying at shell height on the basking slate reads in the low 90s. The thermostat probe sits beside it, and a second thermometer at the cool end confirms the gradient. Fix the lamp so it cannot be knocked down onto bedding, and check the fittings weekly; a lamp that slips a few centimetres quietly turns a safe hot spot into a burn risk.
Holding a gradient in an open tortoise table
The classic open-topped tortoise table loses heat upward, which is fine — the gradient survives as long as the warm end is genuinely warm and the room is not cold. In a chilly room, standing the table away from draughty floors and exterior walls does more than fitting a bigger bulb. Provide a hide at the cool end and an open basking slate at the warm end so the tortoise chooses; deep substrate lets it bury down on cold nights and buffer itself. If the whole table reads in the 60s on a winter morning, the answer is a ceramic emitter on a thermostat for background warmth, not a hotter basking bulb that scorches one spot while the rest stays cold.
Your tortoise's behaviour is the second thermometer
A Hermann's that warms up properly basks flat under the lamp in the morning — legs spread, neck out — then grazes, walks and retires to the cool end or its hide as the day peaks. One that camps under the lamp all day is telling you the rest of the enclosure is too cold; one that never basks and hides constantly may be too hot overall or unwell. Cold, sluggish mornings that never lift, or a tortoise that stops eating as the evenings draw in, are prompts to re-measure the gradient before assuming anything else. When everyone in the house knows the target numbers, nobody 'helps' by moving the lamp. On KinsLe, Family Sharing gives the relatives you pick access to its profile, and that access stays with family you have chosen alone.