Last night was very hot! We don't have an air conditioner in my bedroom. Usually, we sleep with our fan on, our windows open and have an ice pillow. But we gave all that up because it was too hot! So we moved ourselves to tatami room which is our living room with the air conditioner. We layed our futon and slept. When I woke up this morning, my back hurt a bit. Tatami room is very cool but sleeping in the bed feels more comfortable.