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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