Ask the question at cage level and the answer gets practical fast, because a hedgehog does not live in your room's average temperature. She lives at floor level, inside a specific enclosure, often against one specific wall, and that microclimate can sit several degrees away from the number on your hallway thermostat. Getting her cage temperature right is mostly a matter of measuring in the right place and heating under thermostatic control, then reading her behavior as the final check.
The Range and Where to Measure It
The enclosure holds steadily in the low-to-mid seventies Fahrenheit, about 72 to 79 °F, day and night, verified on a thermometer inside the cage. Put the thermometer at her height, away from the direct output of any heat source, and glance at it morning and night until checking becomes reflex. A reading taken beside the heat source flatters the whole setup, while a reading inside her sleeping house tells you what she actually experiences during the day, when she is curled up and most vulnerable to a slow chill.
Hold the range through the night, not just the evening. Hedgehogs are active after dark, eating, drinking, and running, and a cage that is warm at bedtime and cold by three in the morning fails them during their busiest hours. Houses with overnight heating setbacks are the common trap, and the fix is heating the cage itself rather than heating the whole house for one small enclosure.
A Heat Source on a Thermostat, With a Gradient
Run a heat source on a thermostat, always, because an uncontrolled heat source swings between too hot and off, and a hedgehog cannot tell you the mat under her bedding has overheated. The thermostat probe sits where she sleeps or rests most, the heat source switches on and off to hold your set range, and you test the setup by reading the in-cage thermometer at several times of day before trusting it. Position the heat to create a warm end and a cooler end inside the cage, both within her range, so she can shuttle between them as she would across a natural burrow system. Her sleeping house usually belongs at the warm end, with food, water, and wheel spread so she moves through the gradient as part of her normal night.
Never rest a heat source under the entire floor, because she then has nowhere cooler to retreat if she feels hot, and never rely on room heating alone if your house cools sharply at night. Check cords and fittings weekly for chewing or shifting, and keep a backup plan ready for a power cut. These are small habits, but temperature control for this species is a system, and systems fail at their neglected edges.
Reading Too-Cold Signs and Acting
Learn what too cold looks like so you can act early: wobbling on her feet, unusual inactivity during her active hours, and a cool belly when you handle her are signs to act on, never a diagnosis of any particular condition. The response is practical and immediate: check the thermometer, confirm the heat source is running and the thermostat is set correctly, warm the cage back into range steadily, and watch whether she perks up, eats, and moves normally over the next hours. If she is curled tight and unresponsive, warm her gently and gradually against your body under a fleece while you call your vet, because a deeply chilled hedgehog needs professional guidance, not just a warmer room.
Keep a short log of readings and behavior for the first weeks and whenever the seasons turn, since a hedgehog who gradually eats less as readings drift downward has shown you the connection in writing. Share that log with anyone who feeds or checks her while you travel, with the range written at the top so a helper never has to guess what normal means for this cage. A helper-facing record works well in KinsLe via Family Sharing, since the target range and recent readings sit on her profile where a sitter will actually look.