Cheese and crackers
If your mom gave you hot milk during a childhood bout of insomnia, she’s a smart lady (but you knew that already), since dairy is also high in tryptophan.
That said, tryptophan gets triggered into working its sleepy magic through carbohydrates. That's why cereal and milk or cheese and crackers both make for great Sandman snacks.
Though you might be tempted to turn these foods into one big, unholy banana-cheese-rice casserole, sleep expert Dr. Thomas Penzel advises against eating a big meal before bed -- even if it's a banana split (dairy and bananas and nuts are good, right?)