Try to look at it like this.... If you're truely training, then you're paying attention to your caloric intake. If you've met your daily allowance, drink water. You're more than likely thirsty, and not hungry if you've eaten enough based on your training/diet. Your body will end up using that water to help digest and carry the proteins to your muscles while you sleep. You'll wake up with a head that's more clear if the last thing to flow through your body before bed was water.

If you have to eat something... The banana would be a pretty good choice.