Sleep is not a period of uniform inactivity. The two basic types of sleep, REM and Non-REM (NREM), include a total of five stages that we move in and out of as we sleep.
Therefore, Sleep architecture describes the components of our sleep; stages and cycles and their interrelationships. Basically, there are two different states of sleep: Non-Rapid Eye Movement sleep (NREM) and Rapid Eye Movement sleep (REM). The differences between NREM and REM states are based on behavioral and physiological characteristics. Together, NREM and REM include a total of five stages that we move into and out of as we sleep. The duration and quality of these stages can vary greatly, depending on age, health, sleep hygiene, and the individual sleeper.