Each complete sleep cycle takes from 90 to 110 minutes.
Your brain acts differently in eachstage of sleep.
Stage 1
Stage 1 sleep is light sleep.
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You experience a drifting in and out of sleep.
you’re able to be easily woken up.
Your eye movement and body movements slow down.
You may experience sudden, jerking movements of your legs or other muscles.
These are known ashypnic myocloniaor myoclonic jerks.
These sleep starts can give a sensation of falling.
They are triggered by the motor areas of the brain being spontaneously stimulated.
Stage 2
Between 45 and 55 percent of your time sleeping is spent in stage 2 sleep.
There will also be brief bursts of rapid brain activity called sleep spindles.
Stage 3
Stage 3 is known asdeep sleep.
During stage 3 sleep, it can be very difficult to wake someone up.
In this stage, the brain is making slow delta waves almost exclusively.
Your eyes will move rapidly, and your muscles become immobile.
Heart rate and blood pressure increase.
Men may develop erections.
About 20 percent of sleep is REM sleep for adults.
While we dream in all stages of sleep, it is more common and intense during REM sleep.
You are also more likely to recall REM dreams than dreams in any other stage of sleep.
This sleep phase begins about 70 to 100 minutes after you fall asleep.
The first sleep cycle has a shorter phase of REM sleep.
Toward morning, the time spent in REM sleep increases, while deep sleep stages decrease.
Researchers do not fully understand REM sleep and dreaming.
They know, however, that they are important in the creation of long-term memories.
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