I'm sure there are physiological reasons for weight gain in insomniacs, but I put some of it down to extended hours available to eat!
Here it is, 3am, I'm wide awake and hungry. I used to have middle-of-the-night denial. I figured that eating at night didn't count, either towards yesterday or tomorrow.
Guess a cup of tea and a few nuts will help with the hunger, but no more denial!