P.R how much sleep are you getting each day? Real sleep uninterrupted?
I have no idea how anyone can survive on Bulldogpup's system

I used to do 5 or 7 x 8hr nights and sleep minimum 8hrs in the day. Cold dark winter days, up to 12hrs
Back to P.R: if you only do 2 it is worse as you don't get a system going. The more nightshifts in one roster, the better.
- a nap before work really helps - like 1hr sleep after dinner, then shower and off to work
- sleep as much as possible after 1st n/shift to get body clock reoriented. Sleep as long as you can, might mean a bit dehydrated in the day though but I used to do 6hrs at least, up for a couple of hours then back to bed for 3 or 4 hrs even if I didn't feel 'that tired'. Invariably, I slept.
- no caffeine in the latter part of your shift!
- some people say maintain the same eating patterns regardless of time - so eat breakfast before work and dinner after work (I never tried it but many swear by it. I can see how a roast dinner and beer at 0600 helps one sleep though... mmmmmm)