The reason is they cannot fire me that easily. Often when I slept only 3-4 hours for days, I am "loopy" and irritable- bound to make mistakes. Further, I may take a med. leave of absence at some point. I do not advertise my condition but it was a strategic move, I want to retire/last as long as I can...I have been there 10-years, I need 3-4 more.