Working nights in any industry is hard I'm sure. I worked night shift for most of the winter at the FBO I work at part time at and it was tough. It me four or five days to adjust to the schedule, and only one or two days to get back to normal. The hardest part was staying awake once the sun came up. I had a FX F/O notice me nodding off while standing on top of the truck fueling a DC-10 that was turning one morning. Not good. I'm happy I don't work that shift during the week any more. I still do it on the weekends because they want a warm body there. I clock in and go to sleep.