Sleep is a state consisting of several different stages of reversible disconnection from the environment with accompanying reduced consciousness, atonia, and metabolic changes. These stages are primarily divided into rapid-eye-movement (REM) sleep, which is characterized by classic ocular saccadic movement and fast-wave EEG patterns reminiscent of wakefulness, and non-rapid-eye movement (NREM) which can be subdivided further into three stages each distinguished by distinct EEG wave patterns. Normally an individual will progress through a predictable cycle of stages beginning with wakefulness, then through each stage of NREM sleep before quickly reversing through the stages to enter REM sleep.

The maintenance of appropriate sleep architecture appears to play an important role in promoting physiological and mental health. Such health benefits may include modulating memory, emotion, and cognitive integration of stressors and mechanisms are in place to restore sleep homeostasis if sleep is disrupted. One of these mechanisms is REM rebound, which refers to the compensatory increase of the frequency, depth, and intensity of rapid-eye-movement (REM) sleep following sleep deprivation or significant stressors. Several experimental studies utilizing EEG and hormonal measurements have illustrated that human and animal participants who experience sleep deprivation or significant stressors will experience increased frequency and intensity of REM sleep to compensate for said deprivation.