If your bed is positioned directly over a floor vent, you can likely feel cold air coming up through the floor and causing your bed to be cold. There are a couple ways to redirect that air so you can stay warm while you sleep.
One option is to place a cardboard box or small blanket over the vent. This will help to block the airflow and keep the cold air from coming up.
Another option is to adjust the settings on your furnace. If your furnace has a “fan” setting, you can set it to “on” which will cause the furnace to circulate the air in your home and hopefully redirect some of the cold air away from your bed.
If you have a floor vent that you can’t redirect, you may want to consider investing in a bed warmer. These are small pads that you place under your sheets and they help to radiate heat, keeping your bed warm and toasty.