nocturnal!!!

I work 12 hour night shifts, so the day I work sleep till about 11am and then am up until the next day at 9am, so about 22 hours awake. I do find I need to eat every 6 hours or so, so I end up with 4 meals instead of 3 on those days. If this is going to happen, you just need to plan for it- keep the meals that much smaller so you still have room left for that last extra meal. (In my case it's easy; the day after a night shift I come home, have breakfast, sleep through lunch, and get up at dinner time, so I end up with one extra meal the day before and one less meal the day after, so it works out.)

If you're consistently up at 3am you probably need 4 small meals instead of 3 larger ones.

With respect to helping you sleep, make sure you're exercising in the morning (put that early wake-up time to good use!) and not at night; exercising to close to bedtime will interfere with your sleep.