The eating and drinking of milk (or anythign heavy) is because the stomach requires at least an hour and a half to digest, and when it does it will force your body to stay awake. The alcohol and caffein are (obviously) stimulants that will keep you awake (unless you have ADD, then you might try a little caffein before bed, as it will make you sleepy). Similarly, watching/listening to stuff will stimulate the brain and inhibit sleep as well.