A bedroom that stays cold at night while the rest of the house is fine is a common complaint, and it usually has a plain cause. Someone local can often find it in one visit, and you can guide them from far away if you know what to look for. The signs at home are simple: extra blankets piled on the bed, the bedroom door left open, or a remark that one room never warms up.
Local option: New Plan Care gives families in the St. Louis area in-home help so a parent can stay home: companionship, help with bathing and dressing, meals, and overnight care. Call (314) 405-0887.
Measure before you change anything
Place a thermometer at bed height in her room and another near the doorway, then read both at the same time of day for a few days. A room that reads several degrees colder than the hallway points to airflow, not to a thermostat that is failing. Write the readings down so you can compare them on your next call.
Check the vent and the door
Have someone local confirm that the heat register in her room is open and not blocked by a rug, a dresser, or a bed skirt. Check whether the door closes tightly, because a shut door can cut off the air that returns to the furnace, which leaves the room starved for heat. Look at the window for drafts by holding a hand near the frame and the seam at the sill.
Look at the thermostat's location
Ask where the thermostat is mounted. If it sits in a room that gets sun or near a heat source, it may tell the furnace the house is warmer than it is, and the far rooms will run cold. Ask whether the thermostat can be read from the hallway without a tool, and whether she can reach the controls. Do not change settings remotely without telling her and the local helper first.
Space heaters need a rule
A small heater can warm a single room, but it needs its own rules. Place it on a flat floor, at least a few feet from the bed, curtains, and bedding. Use an outlet directly, not an extension cord. Check that it shuts off on its own if it tips over. Do not leave it running in a room where no one is awake to notice a problem.
Tonight
Ask a local person to check the register, the door, and the window seam, and to send you a photo of each. Set the two thermometers for one night and send yourself the readings in the morning.
What to take to the doctor
If she is cold for long stretches, cannot seem to warm up even under blankets, or seems unsure whether the room is cold, tell her doctor how long this has been happening and what the room readings were. Those details help the doctor decide what should be checked, and they are more useful than a general report that she is always cold.