@Karnythia Staying warm while sleeping: use lots of blankets/comforters. Don't wear lots of layers to bed, they can trap sweat and oil and you'll kick off the blankets then get cold. Wear a toque or "beanie".

Use rolled up towels or t-shirts as draft excluders on your windows and doors.

If your bed is against an outside wall, move it away from it.

If you have some, hang rugs and spare blankets on the outside walls in your house. It's old school in the extreme, but it will create an air barrier between the cold transfering through the wall and the warm air in the house. Covering windows on the inside has the same effect.

Whatever you do, DO NOT burn charcoal of any sort inside your house. Or wood if you don't have a fireplace. The chances of suffering from carbon monoxide poisoning are huge and this kills whole families every year. Don't do it.

Past that, drink lots of hot drinks and warm water. You'll burn less energy than if you drink cold drinks.

And for clothes, layer up. Sweatpants and sweatshirts/hoodies are going to be your new besties.