Well first off its not really true. It's somewhat true depending on what you eat but something like pop corn is ok. All of my dorm mates eat before sleeping and it doesn't affect you in any noticeable way at all.
You could eat foods which are not heavy in fat or sugar. Fruit is good, veggies are good and an ounce of protein is good, but not more than that or you could have trouble falling asleep. One cup of carbs are good due to converting to serotonin and helping to induce sleep.