Non-rapid eye movement sleep (NREM sleep) is a phase of sleep characterized by the absence of rapid eye movements. It is divided into three stages, ranging from light sleep to deep sleep. During NREM sleep, the body undergoes various restorative processes, including tissue growth and repair, immune system strengthening, and energy conservation. NREM sleep plays a crucial role in overall health and well-being. It helps consolidate memories and supports cognitive functions. This phase of sleep typically accounts for about 75-80% of total sleep time in adults, making it essential for physical and mental recovery.