It is not comfortable but inside houses you do not freeze to death like that. Sleep in your clothes, buy an electric heater next to your bed, get an electric blanket etc. I slept for quite a long time like that in the Netherlands because my mates squat building had no heat. That was during one of the coldest winters where all canals in Amsterdam were frozen enough to skate on. So yeah, not comfortable but freezing to death is not happening if you just take some care.