Over time, we have discovered that rather than serving as a passive state, sleep is the time that many bodily process take place. As you sleep, you cycle through two main processes: REM sleep and non-REM sleep.
To begin, REM refers to rapid eye movement, and this occurs differently among sleep stages. Brain and body activity change throughout sleep stages, and throughout a sleeping “cycle”, people are expected to transition through the 4 stages of REM and non-REM sleep in a particular pattern.
The following table explains the differences between REM and non-REM sleep as well as how your body reacts to these specific stages:
REM
non-REM
Rapid eye movement takes place.
A person will enter an REM sleeping stage after having gone through the non-REM processes.
Typically, in this stage, a person’s eyes move underneath their eyelids.
This is considered the state in which most “dreaming” takes place.
Some studies support the idea that information is stored for long term memory during this sleeping stage.
This stage takes up a larger proportion of sleeping cycles among younger people (and begins to decrease with age).
Rapid eye movement does not take place.
There are 3 distinguished stages of non-REM sleep:
N1 stage: In this stage, an individual is beginning to enter a sleeping state. They will experience drowsiness as well as signs of light sleeping. Muscle relaxation, slower breathing as well as hypnic jerks are common in this stage. It is estimated that the N1 stage only makes up around 5% of one’s sleeping cycle.
N2 stage: The N2 stage makes up over half of one’s sleeping cycle. This is considered another form of relatively light sleep in which muscles relax, heart rate/breathing slows, and eye movement decreases even further than they did in N1.
N3 stage: This is a deep sleeping stage where blood pressure and muscle activity decrease, and there is no eye movement. The body becomes less responsive to outside factors, making one harder to wake up. About 15% of a person’s sleeping cycle consists of this stage.
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