For almost all of history, sleep was thought to be little more than not awake. It was simply some time that you weren’t conscious and mostly manifested at night time. Now, on account of pioneering research done throughout the last few years, sleep is regarded as a critical element of human well being and has several parts, or stages, that had been not formerly identified.
In fact, sleep occurs in very distinct stages that continually cycle throughout the sleeping period. How much rest you get is really a function of both total time spent in sleep AND the length of each of the various stages too. Definately not being unaware or unconscious, a persons brain remains active during the entire sleeping period and every one of the various portions of sleep is measured with a one of a kind pattern of brain waves.
At its most basic, sleep is comprised of two basic parts termed Rapid Eye Movement (REM) sleep and non-REM sleep and that is sub-divided in to four additional stages.
Normally we begin sleeping in what is termed stage 1 non-REM sleep. In this portion of the sleep cycle, sleep is simply not deep and you’re easily awakened by disturbances. Physically, during this stage, eye movements are really slow and there is almost no muscular activity.
Next, you enter stage 2 non-REM sleep. In stage 2, eye motions stop completely and your brain waves slow with intermittent outbreaks of more rapid waves.
Soon you enter stage 3 non-REM sleep. This level is noted by even slower brain wave activity, but nonetheless with very infrequent spates of enhanced activity.
As soon as stage 4 non-REM sleep arrives the brain is creating even slower brain waves almost exclusively.
Stages 3 and 4 are thought of as deep sleep which is difficult to be woken up. It is this part of the sleep cycle that is viewed as probably the most restorative overall and most necessary to be well rested and energetic during the next day.
In REM sleep, the eyes shift rapidly behind closed eyelids and breathing is much more shallow, and fast. Also, one’s heart rate and blood pressure levels increase plus your extremities are paralyzed temporarily to forestall acting out the dreaming that’s most prevalent during the REM stage.
The initial REM stage occurs about 90 minutes after dropping off to sleep and this cycle of REM and non-REM repeat continuously through the night.
As the night wears on REM stages become longer and stages 3 and 4 of non-REM sleep become correspondingly shorter so, each morning, you will have spent the majority of your sleep time in stages 1 and 2 non-REM sleep and in REM sleep as well.
In terms of percentages, stages 1 and 2 non-REM sleep make up almost 50% of sleep time, stages 3 and 4 and REM sleep are about 25% each.
Learn more about sleep, sleeping disorders, and sleep apnea at Sleep Apnea Symptoms.