Just as there are several different types of headaches, there is also a wide variety of causes for each type of headache. There are over 150 types of headaches; however, there are only three major types of headaches, which are also known as primary headaches. With that in mind, the causes of each of the three types of primary headaches are as follows: - Cluster headaches: the causes of cluster headaches are relatively unknown, as it is not associated with any known triggers. However, alcohol use can increase the intensity of cluster headaches, and some medications may trigger cluster headaches. - Migraine headaches: while the precise cause of migraines is unclear, there are several known triggers of migraine headaches, including changes in sleep pattern, daily use of pain-relief medication, dehydration, emotional stress, exposure to smoke or strong scents, excessive caffeine intake, flashing or fluorescent lights, hormonal changes, overexertion, and sensitivity to various chemicals or preservatives in food. - Tension headaches: the exact cause of tension headaches is also unclear, but some known triggers include anxiety, bright sunlight, certain smells, dehydration, fatigue, lack of exercise, missing meals, noise, poor posture, and stress.