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Definition
A cycle of approximately 90 minutes consisting of NREM and REM stages, repeating 4-6 times per night. REM duration increases with each cycle, and dreams become more vivid.
Related Terms
REM Sleep
Rapid Eye Movement — the sleep stage characterized by rapid eye movements. The majority of dreams occur during this phase. The brain is highly active while the body experiences temporary paralysis.
NREM Sleep
Non-REM sleep stages. Consists of three phases: light sleep, medium-depth sleep, and deep sleep. Dreams can occur in these stages but are typically less vivid and shorter.