This was in Georgia, which is very hot and humid in the summer, and initially we had trouble sleeping because the room just stayed too hot and humid, especially when it was warm.

I have no idea why we did this, but one day we took all the cans of sodas out of the cardboard boxes and threw the boxes out and took other food items out of the cardboard boxes and repackaged some of it in Ziploc bags. And suddenly the room was cool and dry enough to be comfortable.

We thought we were imagining this. Like "Noooo, that can't be."

But there happened to be a thermometer in the window of this room and on subsequent occasions we were able to determine by repeating this that the temperature consistently dropped five degrees Fahrenheit whenever we removed all the cardboard from the food supplies stored in our room.

So it eventually became policy to take everything out of the cardboard box and throw away the cardboard box right after we got all the groceries home. We still do this.

Removing cardboard, etc, drops the temperature and humidity and most likely it is because cardboard et al is more or less slowly rotting. Kind of the same reason hay bails catch fire.