Sleep cycles are recurring phases that the brain goes through while we sleep. Each cycle lasts about **90 minutes** and includes both **Non-Rapid Eye Movement (NREM) sleep** and **Rapid Eye Movement (REM) sleep**.
During this phase, heart rate slows, muscles relax, and brain waves begin to slow. It acts as a transition into deep sleep.
This is the most restorative phase of sleep. The body repairs muscles, tissues, and strengthens the immune system. Deep sleep is crucial for physical recovery.
This is the dreaming phase. The brain consolidates memories, processes emotions, and helps with problem-solving skills.
Understanding sleep cycles is crucial for improving sleep quality. Waking up **in the middle of a deep sleep stage** can cause grogginess, while waking up at the end of a cycle helps you feel refreshed.
Studies show that **individuals who align their sleep with natural sleep cycles** experience better cognitive function, improved mood, and stronger immune systems.
Learn more in our Sleep Research section.
On average, adults should aim for **5-6 full sleep cycles per night** (~7.5 to 9 hours of sleep).
REM sleep helps with memory consolidation and emotional processing, making it crucial for learning.