How well insulated is your apartment? Does it have double pane windows? Or, better triple pane?

The temperature drops, and if you've got it set to a temperature the heater is going to turn on, as the walls get cold.

But, your biggest bills will be Jan-Feb.

If your paying for the heat, than the manager has no incentive to add insulation. Find an apartment where the heat is included, then you'll know the landlord will put in a high efficiency heater, better windows, and better insulation.