Many factors have been identified as migraine triggers. The normal hormone fluctuations which occur with regular menstrual cycles may predispose some women to experience migraine headaches. Some types of oral contraceptives (birth control pills) can trigger migraines. Various foods, including red wines, aged cheeses, nitrates (preservatives used in smoked meats), monosodium glutamate, artificial sweeteners, chocolate, and even dairy products have been implicated in triggering migraine headaches in susceptible individuals. Some patients find that oversleeping, stress, or exposure to strong stimuli such as bright lights, loud noises, or strong smells can lead to a migraine headache. Changes in barometric pressure have been described as leading to migraine headaches as well.