Like V4F stated, it is standard procedure for areas in enroute centers, usually 6-8 sectors to be combined to one position at night. Normally 10 pm to 6 am. The controller would work 700 AGL to above 60,000. We worked the SR71's in the day and still work TR2's and other U2 models out of Beale not to mention the drones. Many times at night while working area D you would be vectoring for the ILS at STS and running a refueling track near RBL, while also handling the enroute traffic etc. not unusual to have 25 AC on Freq. But the airspace was Hugh, not many conflicts.