Sierra -
Welcome to the boards! I guess the first question is, what is your current diet, training, cardio regimen? And tehn what are your goals?
Your diet and eating schedule should dictate when you get hungry. Cravings for carbs or sweets can result from other things such as hormones as well (e.g. that time of the month and others). For example I believe you might find that women tend to have a craving for carbs while men have more of a craving for salt.
I would say that carbs like cereal are a bad thing to be eating in the middle of the night. Particularly processed carbs (just bad all around) and simple carbs just give you a sugar spike and then your insulin levels are fluctuating. (Though you might fall asleep better from that!) Carbs are best eaten in the earlier part of the day. Too many extra carbs will just turn to fat. Granted, a bowl of cereal in the middle of the night won't kill you, but if you are trying to achieve some weight loss / body fat loss goals, it will interfere.
Generally it is optimal to eat 5-6 small meals/day spaced out every 2-3 hours - good carbs like oatmeal in the morning, some complex carbs later like brown rice or sweet potatoes and lots of carbs from green leafy vegetables during the day. Cut out the complex carbs before 3 PM. Avoid processed food if you can (e.g. junk food, sugars, white bread, white rice, etc.). Eat good clean protein and dont' be afraid of protein - lots of women don't eat enough protein and go for the salad loaded with dressing and junk like that. And drink lots of water. If you get your body used to the 5-6 meals/day, it stops craving things in the middle of the night.
Another thing to consider is that you are getting enough calories too! If you dont' eat enough, even on the 5-6 meals/day, then your body will be starving and loading it with carbs in the middle of the night will only make you feel lousy. It just sort of bogs down your metabolism.
So alternatives to the midnight munchies? Mix up some very low or zero carb protein mix. The body processes protein pretty decently overnight. Otherwise if you eat well during the day, you shouldn't get the carb cravings. And how much of those midnight munchies are just out of habit?? I have to fight the urge to get home from work and relax in front of the TV w/ a bowl of ice cream - I've been dieting a la contest prep for more than a year and I still can't toss this urge - part of my old really bad eating habits that just won't go away!
Good luck - I'll be interested to see how other people on this board deal w/ this!