Stages
of Sleep: The Time Your Body Needs to Heal Itself
Sleep
is one of life’s simple pleasures. When you think
back to childhood, you may remember how easily sleep came
to you. All you would have to do is close your eyes and
dream the night away. Interestingly, as easy as it happens
for babies and children, sleep is not a simple process of
“shutting off” the brain and body. On the contrary,
sleep is an active state. Sleep comes to your mind and body
in four different stages, and each of the four stages of
sleep has an important function to your physical and mental
well-being. It is these stages of sleep that may become
disrupted as you age, leading to many common
sleep disorders.
The
four stages of sleep enable your mind to alternate between
two basic states: rapid eye movement sleep (REM sleep) and
non-rapid eye movement sleep (NREM sleep). All four stages
of sleep consist of NREM sleep. After the four stages of
sleep, you will enter REM sleep for a period of time, and
then you will cycle back into the four stages of NREM sleep
again, followed by another period of REM sleep, and so on.
Throughout the night, a normal sleep pattern would be to
alternate between the four stages of sleep and then REM
sleep. Insomnia symptoms
may occur during any stage of sleep or insomnia may also
interfere with REM sleep.
Therefore,
NREM sleep is made up entirely of the four stages of sleep.
Each stage may last from 5 to 15 minutes. During Stage One,
you may be easily awakened and feel as if you never slept.
Stage Two is a light stage of sleep in which your heart
rate slows and your body temperature decreases. This is
a sign that your body is preparing for the deeper stages
of sleep.
Both
Stage Three and Stage Four are deep sleep stages, known
as slow wave or delta sleep. Stage Four provides a deeper
sleep than Stage Three. It appears that Stage Three and
Stage Four are the stages of sleep when the body repairs
itself, builds muscle and bone tissues, and strengthens
the immune system.
After
the four stages of sleep, REM sleep occurs. Your first period
of REM sleep should be about 10 minutes. As the night progresses,
each of your REM sleep periods should be longer, with your
final REM sleep lasting up to 60 minutes. As the name implies,
REM sleep is a time when your eyes move rapidly in different
directions. You’ll likely experience intense dreaming
activity during REM sleep.
All
four stages of sleep, plus REM sleep, enable your body to
rest and restore energy levels. The effects
of sleep deprivation can be dangerous because giving
your body enough time to sleep is fundamental to good health,
stress relief, and recovery from illness.
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