It was a good thing mom and dad had a king-sized bed.
Nowadays, nearly everyone has a whole home HVAC system and zone control.
When I was growing up in the 50s and 60s, we didn’t have heating in our upstairs.
We counted on one main register that sat in the middle of the hallway to pull enough heat from downstairs to warm our bedrooms. I remember times when my dad would block off the register, mom would put curtains up to the stairwell, and we would all sleep in the living room to stay warm and cozy. It was a camping in the middle of your living room type of night. I remember one particular evening, when it was nearly 20° below zero outside. Our windows were covered with ice, and we couldn’t sleep because we were shivering so badly. We didn’t know the furnace had quit working, but dad did. One by one, the four of us kids crept over to mom and dad’s room and quietly curled up next to mom. It wasn’t until my older sister came over and hopped in bed that we realized daddy wasn’t there. Mom told us to curl up underneath the covers and try to get some sleep while she threw on her robe and headed downstairs. Several hours later, I heard mom and dad talking as they were coming up the steps. Dad was talking about how they had to get a new furnace because he didn’t want to need to go without heat again. Mom agreed about the furnace, and she laughed and asked what they were going to do about sleeping tonight? Dad said they didn’t need a furnace tonight, as they both crawled into the one side of the bed where we hadn’t spread out.