Fold the comforter down before changing the whole bed.
Mattress protectors can change warmth.
If it is warm only at bedtime, the room may be storing daytime heat.
Start with the top layer
Fold the comforter lower, switch to a lighter blanket, or leave one foot area less tucked. The top layer is the easiest place to test because it can be changed without buying anything.
Check sheet texture
Some sheets feel warmer or clingier than others. If the bed feels too hot, try a smoother or lighter sheet set before replacing the mattress or comforter. Also check whether a mattress protector is trapping warmth.
Move air early
A fan at bedtime helps, but moving air earlier in the evening can keep the room from feeling stale. Open interior doors, use safe window habits based on local conditions, and keep vents unblocked.
Reduce daytime heat storage
Close curtains during strong sun, avoid leaving warm electronics running near the bed, and keep heavy blankets folded away until needed. A bedroom can hold heat long after the rest of the home cools.