Try and leave 3 hours between your last meal and going to bed.
This gives the body plenty of time to digest your food. If you're reaching for a late-night pizza it's going to take your body longer to burn off the carbs than it would when you're active and awake.
It also means that you have less chance of suffering with indigestion or heartburn.
So, close your kitchen early tonight and see if it makes a difference to your sleep.