Stage of Sleep

Definition

Each stage of sleep is characterized by different patterns of brain activity and physiological changes.

Related terms

Rapid Eye Movement (REM) Sleep: This stage is associated with vivid dreams and rapid eye movements.

Non-Rapid Eye Movement (NREM) Sleep: This refers to all other stages of sleep besides REM, including lighter sleep (stage 1 and 2) and deep sleep (stage 3 and 4).

Hypnagogic State: This transitional state between wakefulness and sleep often includes brief hallucinations or jerks called hypnic jerks.