Final answer:
Normal sleep is composed of REM and non-REM (NREM) sleep, which include stages with different brain wave patterns.
Step-by-step explanation:
The two phases that make up normal sleep are Rapid Eye Movement (REM) and non-REM (NREM) sleep. During the REM phase, characterized by rapid movements of the eyes, the brain waves are very similar to those observed when a person is awake, and dreaming occurs. In contrast, NREM sleep is subdivided into three stages distinguished by different patterns of brain waves, ending with the deep sleep stage marked by low frequency, high amplitude delta waves.