Think floor temperature, not air temperature
A leopard gecko digests on belly heat, so winter care is judged where he lies, not by the room thermometer. The floor of his warm hide should sit at 88–92°F, delivered by a heat mat under the enclosure and controlled by a thermostat, with the probe on the floor inside the hide where his belly actually rests. The rest of the enclosure can run much cooler — leopard geckos come from arid country and are built for warm ground under a cold night sky — so a house that feels chilly to you can still be perfect gecko weather at floor level.
The winter appetite dip
Most leopard geckos eat less as the light fades and the house cools, skipping meals they would have hunted in July. Keep offering on his normal schedule, keep dusting his insects with calcium and vitamins exactly as usual, and don't chase a reluctant gecko with ever-larger feeders or constant bowl changes. A healthy adult can miss a run of meals without harm; what he should not do is shrink. Weigh him every couple of weeks through winter — a small kitchen scale and a tub he already knows — and let the numbers, not the untouched dish, decide whether you worry.
Read the tail
A leopard gecko carries his savings account in his tail: plump and firm means reserves are good, and a tail that stays plump through a quiet eating season means the season is all that is happening. A tail that visibly thins week by week, especially alongside lethargy, dull color, sunken eyes or a gecko who stops coming out at night, is a different picture — that combination earns a vet visit, and sooner rather than later. Stuck shed on the toes is the other winter tell: dry air leaves old skin gripping the toes, where it can cut off circulation, so provide a humid hide and check his feet after every shed.
Nights, lights and quiet houses
A nighttime drop into the low seventies needs no night heater for this species, and his light cycle can simply follow a natural winter day — he is a dusk-and-dawn animal who does most of his living in dim light anyway. Keep his water dish filled, his warm hide's floor temperature checked weekly rather than assumed, and his enclosure out of drafts and off cold windowsills, which can chill one end of the tank unevenly. It is a low-drama winter when the basics hold: warm floor, plump tail, clean sheds. In KinsLe, Family Sharing lets you give relatives you pick access to his profile, so a relative doing his fortnightly weigh-in can open that profile beside the kitchen scale.