Sleep is an essential, active state of rest for the body and brain, characterized by altered brain wave activity and physiological changes. It consists of two main types, non-rapid eye movement (NREM), also known as "quiet sleep." NREM is divided into stages that become progressively deeper. It is during this time that heart rate and blood pressure decrease, and the body focuses on repair and restoration, and rapid eye movement (REM), also known as "active sleep." The brain is highly active during this stage, similar to when you are awake. Most vivid dreams occur during REM sleep, while the body's muscles are temporarily paralyzed. It is crucial for cognitive functions like learning and memory consolidation. You cycle between NREM and REM sleep throughout the night, typically beginning with about 90 minutes of NREM before entering REM sleep. As the night progresses, the NREM/REM cycles repeat, with REM periods getting longer. During sleep, the body performs vital functions that help repair tissues and build muscle. The brain uses sleep to clear waste products, strengthen critical neural connections, and sort and store memories, which enables the body to conserve energy for the next day. And release hormones necessary for growth. Getting enough quality sleep is linked to a stronger immune system, better mood, improved concentration, and a lower risk of chronic conditions like heart disease and obesity, which are crucial for physical and mental health.