Certified Polysomnographic Technician (CPSGT) Practice Exam 2025 - Free CPSGT Practice Questions and Study Guide

The correct choice highlights the unique characteristics of REM (Rapid Eye Movement) sleep, which is a crucial stage of the sleep cycle. During this phase, brain activity actually increases and resembles that of wakefulness, indicative of intense brain activity related to dreaming. This is supported by the presence of rapid eye movements, which are a hallmark of REM sleep. Additionally, REM sleep features temporary muscle paralysis, a physiological response that prevents the sleeper from acting out their dreams. This paralysis, called atonia, is essential for safety during this intense dream state.

The other options describe different sleep stages or are inaccurate in their characterization of REM sleep. For instance, decreased brain activity and muscle relaxation are more representative of non-REM sleep stages, specifically deep sleep (NREM), where brain function slows down and physical relaxation occurs. Similarly, slow brain waves and easy awakenings are also associated with deeper slow-wave sleep stages and do not apply to REM sleep. Finally, deep breathing and a lower heart rate are typical of non-REM sleep, particularly during slow-wave sleep, rather than the active state of REM sleep.