What are the two primary phases of sleep?

The two primary phases of sleep are REM (Rapid Eye Movement) and Non-REM sleep. REM sleep is characterized by rapid movement of the eyes, increased brain activity, and vivid dreams; it's a crucial phase for memory consolidation and emotional processing. Non-REM sleep, on the other hand, consists of three stages that progress from light sleep to deep sleep, which is essential for physical restoration, growth, and recovery.

The classification into these two main phases highlights the significant differences in brain activity and physiological functions that occur during sleep. This understanding is foundational in the study of sleep cycles and the impact of sleep on overall health and well-being. By focusing on these primary phases, researchers and clinicians can better understand sleep disorders and the benefits of healthy sleep patterns.