Pumping At Night?

Some nights now my son will sleep through or more often his dad takes the morning shift. Sometimes it works out to be 6 or 8 hours between feedings or pumping. More often than not I only get about 4 hours sleep though. I set an alarm to wake up and pump -usually my son wakes first- but when he doesn't I just keep sleeping. Waking up engorged but we'll rested. Is this bad for my milk supply? Should I get up every 4-6 hours at night for the next year of my life to pump or feed? What do you do?