To understand how our dreams work, we need to first
understand the sleep cycle. Before
we can gather information from our dreams, we need to
understand where those dreams come from, and to do that
we must understand the various stages of sleep and how
they fit together.
The sleep cycle consists of four individual stages,
and every person goes through all four stages each and
every night. The length of each cycle varies from
person to person, but every human being experiences
all four stages of sleep every night.
In general, the dreams that are most likely to be
remembered are those that take place the closest to
waking. Dreams that take place earlier in the
night are almost never remembered. The one exception
to this rule is those dreams that are disturbing enough
to wake the dreamer. If a dreamer awakens in the
middle of a dream, say a particularly vivid
nightmare or a dream about falling, he or she will most
likely remember vividly every detail of the dream.
Let us take a look at the four individual stages
of sleep, starting, logically, at stage one.
The initial stage of sleep is a very light sleep,
and the slightest disturbance can wake the dreamer at
this stage. The first stage of sleep usually lasts
for only a few minutes, and most sleepers move on quickly
to stage two.
The second stage of sleep is much deeper, and it
is much harder to wake the sleeper up at this point.
While the dream state begins in stage two, there
are usually no clearly formed images at this point.
Instead dreams in stage two consist mainly of
vague ideas and images floating around the mind. After
stage two is completed, the dreamer moves quickly on
to stage three.
The third stage of sleep is even deeper than the
second stage. At this stage, the muscles in the
sleepers body have relaxed, and the heart rate and respiration
rate have both slowed down. The sleeper's blood
pressure also drops off at this point, and breathing
is typically even and steady. A sleeper in stage
three sleep is very difficult to awaken, and typically
waking can only be accomplished by a very loud startling
noise or by shouting the sleeper's name repeatedly.
Stage four is the deepest stage of sleep, and the
one in which most dreaming takes place. During
this stage of sleep, it is almost impossible to wake
the sleeper. During stage four of sleep, the sleeper
moves in and out of REM (rapid eye movement) sleep several
times. It is during REM sleep that dreaming is
occurring. The eyes move back and forth rapidly
under their lids, the heart beat and respiration spike,
and brain wave activities increase. Studies have shown that brain wave activity
is higher during dream sleep than it is during normal
Most sessions of dream sleep last for about 10 minutes,
after which the sleeper returns to the normal deep sleep
of stage four. The dreamer will cycle back and
forth between stage four sleep and dream sleep several
times each night, usually repeating the process from
four to seven times on an average night.