I struggle to sleep the night before the first day of shooting on each film I DP. I start mulling over lighting plans and stressing about how I'm going to do it and if it's going to be good enough etc. etc.
Bottom line - I grab a Red Bull on the way to set and just suck it up. I've had to AC on many occasions with only a few hours sleep, and I've even been the victim of a forced call, where we've wrapped at 4am (hour drive home) to have a call time of 10am the next day (hour and a half drive there in peak hour).
You almost get used to it - well, you don't get used to it you just learn to live with it and make sure you sleep heaps when you get a chance.
The worst I've had was tearing down a set after wrap until 6:30am, having to drive home to pick up extra equipment, then drive back to a different set and be there by 8:30am. I didn't get home to sleep until 9 oclock that night, after having been up for about 36 hours.
Suck it up and do the best you can. I've had ACs push through 12 hours of crippling hayfever and crippling hangovers to deliver for me. For some reason, it tends to be a part of the job - not to mention the winter months when one sick crew member spreads the disease to just about everyone on set...
I've often times just taken a couple of weeks off towards the end of the year just to rejuvenate and sleep a little.