The Stages Of Sleep
All Of Us Sleep, But Do You Know What’s
Going On When We Sleep?
When you close your eyes and fall off to sleep,
do you know what's going on inside your body? Although it
might seem that you are resting, not every part of your body
is resting. Especially our brain, it will send out all sorts
of signals, many of which are controlling the various stages
of sleep you'll be undergoing. Eye movements and muscle activity
change throughout the various stages of sleep too.
In fact, there are five stages of sleep and on a good night's
sleep you need pass through all of them for several times.
Although there are 5 distinct stages, the first four stages
are grouped together and classified as the state of non-rapid
eye movement or NREM. The fifth stage is known as the state
of rapid eye movement or the REM stage.
The different states of NREM and REM are distinguished by
the changes in brain wave activity that is happening. REM
is also characterized by irregular but rapid breathing and
heartbeat, a rise in blood pressure, increased brain activity
and virtually no muscle activity.
NREM and REM sleep occur throughout the sleep period. The
sleep that takes place during the first third of a night consists
mostly of NREM while the sleep during the last third is mostly
REM. Usually you will awaken from a REM stage.
Stage 1 is tbe transitional period, which means it consists
of light sleep from which you can easily be awakened. During
stage 1, the cycle of falling asleep and waking can repeat
several times. During this stage, you will feel drowsy and
begin to lose control over your muscles and your eye movements
slow. During this stage, hypnic myoclonia, a sudden contraction
or jerking of muscles might happen.
Stage 2 occupies nearly half of the sleep period. During
this stage the eyes stop moving, brain waves slow down, body
temperature drops and heart beat also slows down. Occasionally
there are short bursts of eye movement.
Stages 3 and 4 are the stages during which the body is in
a deep sleep. These 2 sleep stages are characterized by the
presence of delta waves which are the brain waves that are
extremely slow. Eyes and muscles are completely still during
stages 3 and 4.
The REM stage takes place throughout the sleep period. REM
always follows a period of NREM sleep and makes up for about
a quarter of the total sleep period. The first REM occurs
at the end of Stage 1 and lasts about 10 minutes. The final
REM stage tends to last longer, about an hour. If you sleep
8 or 9 hours, you'll typically experience REM sleep 4 or 5
times. You're able to dream during REM, too.
As mentioned above, these are the stages that happen through
out our sleep. These repetitions are also known as sleep cycles.
Several sleep cycles take place during a single sleep period.
As the sleep cycles progress through a sleep period, the amount
of REM sleep increases. Keeping these sleep cycles from becoming
disrupted is what results in better-quality sleep.
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