What are the rules for unplugging a refrigerator?
When you short cycle the compressor like that it's the worst thing an owner can do to shorten the lifespan of it's compressor.  

The refrigerator compressor uses oil to lubricate the pump. This pump runs very hot. The oil becomes dirtier and dirtier as it travels through the refrigerator tubes and clogs the refrigerant paths making it impossible for the refrigerator to cool. When you short cycle the fridge, it immediately kills the pressure behind the oil from the compressor, and the oil in the pathways must trickle back to the reservoir. with only gravity assistance, so the thicker the oil is the less likely it is to make it back without clogging.

However if you must turn it off in order to sleep, turn the cold temp to off prior to turning the fridge off. All fridge manuals recommend that you do this before unplugging the fridge when moving the fridge. This will help keep the oil flowing back to the reservoir.