Hi April, I'm an RN also and I work nights, I have for the past year. I get to go to Days in October - I am SO happy! I work the 7p - 7a shift. I have dinner before I leave, about 6:00 and it's usually a Smart One and some steamed veggies. I drink either coffee or tea the first few hours I am there. I don't eat again until I take my break, which is usually somewhere around 2 am. I am VERY strict about what I eat then, I always bring it from home and it's steamed veggies that I pop in the microwave and either a tin of sardines or a pouch of tuna (the 4 or 5 oz size). I eat an apple about 6 am.
That late-night meal and my apple basically substitute for my breakfast. When I wake up the next day, it's usually about 2:30 and I eat a "lunch", don't have an afternoon snack, and then eat a normal dinner. I too found I was gaining weight, because like you I was eating an extra meal at night. I found that if I make that a really small meal that substitutes for breakfast, I am OK. Sometimes I find myself feeling hungry around midnight, but I usually so busy that it's easy to forget about it. I work med-surg, I think if I had a less-busy job, the nibbling might be a problem.