The Stairway to Sleep
 As
we put on our pajamas, jump under the covers and get ready to sleep,
our bodies are preparing to replenish our energy through what is
called the sleep cycle. Sleep is divided into two distinct cycles,
non-rapid eye movement (NREM) and rapid eye movement (REM). The
five stages of
sleep occur cyclically. A full sleep cycle has been completed after
the REM stage has ended. Sleep cycles typically last for
100 minutes. A person can complete five sleep cycles in a typical
night's sleep.
- Stage 1 is the transition stage between being awake and
being asleep. For a person not suffering from a sleep disorder.
This stage can take about one to five minutes to occur.
- Stage 2 is a period of light sleep. The body's heart
rate and temperature decreases. At this stage of sleep, the body
prepares to enter a deep sleep.
- Stages 3 and 4 are deeper stages of sleep. Stage 4 is
more of an intense sleep than stage 3. These stages are known
as slow-wave, or delta, sleep.
- Stage 5 is called REM sleep. This stage is distinguishable
from the previous stages of sleep because it is characterized
by rapid eye movements. During REM sleep, the body's heart rate
and respiration speed up and become erratic, while the face, fingers
and legs may slightly twitch. Intense dreaming occurs during this
stage of sleep. This is the final stage of the sleep cycle and
can last anywhere from ten minutes to an hour.
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