Star Wars: 10 Secrets Behind The Death Star You Didn't Know
7. Crew Members Served For Six Years At A Time
As the production was completely classified, long term stints were necessary to assure that crew members weren't able to blab to their more republic-sympathetic friends and family about their time on a space station with planet-destroying capacity.
The Death Star took decades to build, so the staff on board rotated frequently. If you were an officer in the ranks of the imperial army, the technical companion book claims it was a lottery as to whether your time aboard would last anywhere from six months to six years!
Six years is enough time to drive a man insane without a way of relieving stress. Fortunately, the Empire had though of that...