Which sleep stage comprises approximately 20-25% of total sleep time?

The sleep stage that comprises approximately 20-25% of total sleep time is REM (Rapid Eye Movement) sleep. This stage is characterized by increased brain activity, vivid dreams, and physiological changes such as muscle atonia and rapid eye movements. REM sleep is crucial for cognitive functions, memory consolidation, and emotional regulation. It typically occurs multiple times throughout the night, with each REM period gradually increasing in duration as the sleep cycle progresses.

In contrast, the other stages do not fulfill this specific percentage of total sleep time: N1 represents the lightest stage of sleep and usually accounts for a smaller percentage; N2 is the stage of sleep where you spend the most time overall, generally making up about 50% of total sleep; and N3, known as deep sleep, comprises about 15-20% of total sleep time. Thus, REM sleep's distinctive characteristics and its importance to overall health and function highlight why it makes up a significant portion—approximately one-fifth—of total sleep duration.