Asleep . . . but Active?

I came across an article in the New York Times that really caught my attention. It talked about the phases of sleep. The reason why this article caught my eye was because of the drawing and the layout. It was not one of those boring articles where you had to read about two pages of size five font letters! Instead, it displayed a silhouette of a person lying on their side sleeping and there were captions placed above the drawing describing the different stages one goes through while sleeping. I found this article interesting because when we sleep we tend to think we’re “dead to the world,” or at least I think that and I feel that we should know what goes on in our bodies while we are sleeping.
Well the article breaks it down like this: There are five stages of sleep – Stage 1, Stage 2, Stage 3, Stage 4 and Rapid Eye Movement (REM) Sleep. During the first stage of sleep the person can still be awakened and muscle contractions occur. In stage two, breathing becomes regular and body temperature as well as heart decreases as the body prepares to go into a deep sleep. Throughout the third and fourth phase, your heart rate is at its lowest. Sleepwalking or “nightmares” can take place. Bones and muscle are being built and tissues are restored. The most active stage of sleep is REM. The brain becomes very active which allows for dream to happen. Our limbs are effectively paralyzed because a control region in the brain stem sends signals to shut off neurons in the spinal cord, preventing us from acting on our dreams. Body temperature control changes so that no sweating or shivering occurs in response to changes in room temperature. And lastly, the eyes dart around and wouldn’t you think so since this stage is called Rapid Eye Movement? So, I found this article entertaining as well as knowledgeable to know what REALLY happens while I sleep.