I was thinking about what you said about eating when you're up late at night.
First, for me I think it's mostly a bad habit. I THINK I need food to stay awake, but I really don't.
Then again, being awake for more hours in the day means you might legitimately need a little more fuel to keep you body going. I don't think 100 extra calories is going to derail you. So here are my suggestions (not that you asked!):
Start with drinking lots of water or crystal light--I've heard cold water helps your body feel awake.
Try sugar-free jello or popsicles.
Go for a low-cal snack that has protein which stays in your system longer--light yogurt, beef jerky, cheese, nuts, etc.
Try just a few pieces of candy--starbursts only have 15 calories per chew; sometimes I need a little sugar and I don't overindulge on those like I would on chocolate.
When you do give in and eat too much and regret it, just remember that you get to try again tomorrow and a previous mistake doesn't have to ruin the next day too.