Just exactly what is going on in your body when you close your eyes and go to sleep? Even though you are at rest, not each and every element of your body is regenerating and quiet. In particular, the brain is busy producing a variety of signals which are helping manage the different sleep stages. Muscle activity and rapid eye movements adjust while in the various sleep stages as well.
Usually sleepers pass through five stages: 1, 2, 3, 4 and REM (rapid eye movement) sleep. All these sleep stages advance cyclically from stage #1 through REM then begin again with stage 1. A whole sleep routine requires around 90 to 110 minutes. The first sleep cycles every night have relatively short REM sleeps and long periods of deep sleep but, later in the night, REM durations lengthen and deep sleep time diminishes.
Stage 1 is mild sleep in which you drift into and out of sleep and may be awakened very easily. Within this stage, the eyes move slowly and muscle activity slows. With this stage, lots of people experience sudden muscle contractions preceded with a experience of falling.
In stage 2, eye motion stops and brain waves get slower with only an occasional burst of rapid brain waves.
Stages #3 & #4
When a person goes in stage 3, extremely slow brain waves known as delta waves are interwoven with smaller, quicker waves. In stage 4, your brain produces delta waves almost exclusively. Stages 3 and 4 are referred to as deep sleep or delta sleep, and it’s also tough to wake someone from. In deep sleep, there is no eye movement or muscle activity. This is when some children experience bed wetting, sleepwalking, as well as night terrors. In 2008 the sleep industry in the united states got rid of the use of stage 4. Stages 3 and 4 are now referred to as stage 3.
Slow wave sleep occurs mainly during the first half of a night, REM in the second half. Waking up may occur following REM. If the waking interval is of sufficient length, the individual may bear in mind it the following morning. Shorter awakenings may disappear with amnesia.
During the REM interval, breathing grows more rapid, intermittent and shallow, eyes jerk quickly and limb muscle groups are momentarily disabled. Brain waves in this stage rise to degrees experienced if a individual is awake. Also, heart rate will increase, blood pressure level increases, males develop erections and the entire body will lose some of the capability to regulate its temperature. Its during this period when the majority of dreams occur, and, if awoken while in REM sleep, an individual can recall the dreams. Most individuals have three to five intervals of REM sleep each night.
Babies spend almost 50% of time in REM sleep. Older individuals spend up to 50 % of sleeping time in stage 2, about 20% in REM and the other 30% is split among the other three stages. Seniors spend considerably less time in REM sleep.
As sleep research is still a comparatively young field, scientists did not learn about REM sleep until 1953 when new equipments were developed to observe brain activity. Before this finding it had been believed that the majority of brain activity stopped during sleep. Since that time, scientists also have disproved the concept that deprivation of REM sleep can cause insanity and have learned that lack of REM sleep can alleviate major depression even though they don’t know the reason why. The latest hypotheses link REM sleep to learning and memory.