I know that Albert Taylor says that he kept logs of his lucid dreams and habits before bed to keep track of and improve his ability to lucid dream. He states in his book called Soul Traveler that the optimal time to eat a HEAVY meal is 3-4 hours before sleep. Obviously he reported more lucid dreams if he didn't eat just prior to going to sleep.

It makes sense to me in this way; If your body is not busy digesting a lot of food at night it will have more energy to spend inside the brain and keep a conscious enough mind to actually induce lucidity in dreams.