There are four sleep symptoms that patients can have: difficulty with sleep onset, problems occurring during sleep, difficulty awakening from sleep, and daytime sleepiness. These symptoms develop when there is a problem in one or more of the nine fundamental process domains that control sleep. These fundamentalsleep process domains are: circadian, homeostatic, ultradian, developmental, cardiorespiratory, neurological, psychiatric/behavioral,drugs/alcohol, and other medical problems. Successful treatment of the sleep problems depends on the correct identification of the underlying sleep processes that are causing the sleep symptom. The sleep process matrix is a way of organizing one's thinking to accomplish this task.