Sleep is a complex biological process made up of several distinct phases that cycle throughout the night. Light sleep typically occurs first and helps the body transition from wakefulness to deeper stages. Deep sleep is when the body focuses on physical recovery, immune function, and cellular repair. REM (Rapid Eye Movement) sleep is characterized by increased brain activity and plays a role in memory consolidation and mood regulation. NREM (Non-Rapid Eye Movement) sleep includes multiple stages—ranging from light to deep—that allow the body and brain to recharge. Each phase is essential and contributes to overall well-being in different ways. These cycles repeat several times a night, and disruptions can affect concentration, mood, and health. Learning how sleep stages work helps individuals recognize the importance of rest and encourages habits that support more consistent, high-quality sleep.