Sleep ~ Part One in a Series

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Did you know that there are four individual stages of the sleep cycle? They can be determined by an analysis of the brain activity during sleep and shows distinct patterns that characterize each stage. These change throughout the night. The first stage is known as NREM or No Rapid Eye Movement and lasts for about 1-7 minutes. Next is the second stage, also NREM and is about 10-25 minutes in duration. The third is also a NREM and lasts 20-40 minutes. This stage is also known as deep or delta sleep. The Fourth stage is REM and last 10- 60 minutes. In the first stage, the person is relaxing and falling asleep. If not disturbed they will move right into the second stage. The second stage is when the body temp lowers, muscles relax and, breathing and heart rate slows. Usually, a person spends about half their sleep time in this second stage. In stage three the body relaxes even further with muscle tone, pulse, and breathing decreasing even more. This third stage is what experts believe is when the body restores itself and grows. This time may also increase the immune system and other important body functions. As sleep continues these stages get shorter and more time is spent in REM sleep instead. In the fourth stage, or REM sleep the body activity picks up and levels seem more like when you are awake. This time period is believed to be important to cognitive functions like memory, creativity, and learning. It is the time of the most vivid dreams and more active brain activity. Dreams are less common in or intense in other stages. Normally, you enter REM sleep after you have been asleep for about 90 minutes. As the night goes on the REM stages get longer, especially in the second part of the sleep cycle. REM stages make up about 25% of sleep in adults.