I have been working 12 hours nights for a couple of months now. I don't see the exhustion for the last few hours that some have mentioned in the past, but i really think the whole discussion is a prefrence. I am young, just out of school and love my job but don't want to give up being young for the sake of my career. 12 hour shifts give me the opportunity to have a life outside of work. Fortunatly my body has taken well to nights, i get home eat and go to bed, get up eat and go back to work. I prefer to do my three days in a row with nights because i can have a normal "Day" life on my days off.