Drains and toilet gurgle during the night, when it's cold. Air bubles come up the toilet and then it actually drains itself, like the water is sucked out. Then it stops. Is this a sign of a future problem, what's happening? Only happens in the middle of the night around 3 am.

My first thought is that your main line is stopping up... problems do not have a set time to happen so it is more than likely doing it more often than you think... check your main line to start with

Do you have a water softener? Some times the backwash timer on water softeners are set to go off in the middle of the night. And if you sewer is partially stopped up this might explain why your sewer gurgles and the water goes down in your commode.