Dreams may occur at any
of the four stages of sleep, but the most vivid dreams, and the ones most
likely to be remembered in the morning, occur during the REM stage of
sleep. This sleep stage is generally referred to as REM (rapid eye
movement) sleep. The name comes from the eye movements that are observed
during this stage of sleep.
Since the entire sleep cycle repeats at least four and sometimes as
many as seven, times per night, it's therefore possible and even likely
that the same person will experience several different dreams every night.
In most cases, however, the only dreams that are remembered are those that
take place closest to waking. Not remembering dreams, however, does not
mean they have not occurred.
Let's begin our look at the four
stages of sleep.
Stage 1
During the first stage of sleep,
the sleeper's eyes move back and forth in an erratic fashion. For this
reason, this stage of sleep is referred to as REM, or rapid eye movement,
sleep. This stage generally occurs from 90-100 minutes after the initial
onset of sleep. During this period of sleep, the blood pressure rises and
the heart rate and respiration speeds up and may become erratic as well.
During this stage of sleep, the voluntary muscles become paralyzed. This
stage of sleep is the on
e in which
the majority of dreaming occurs.
Stage 2
Stage two is a light sleep, and
it's characterized by non rapid eye movements. During this stage of sleep
the muscles are relaxed and the heart rate is slowed. This stage of sleep
prepares the body for deeper sleep.
Stage 3 and 4
Stages three and four also feature
non rapid eye movements. During stages three and four of the sleep cycle,
the body enters into a deep sleep. You are completely asleep during both
stages, but stage four is more intense than stage three.
All four stages of sleep
repeat themselves throughout the sleep period, generally occurring from
four to seven times. Each time the sleeper enters REM sleep, dreaming
occurs. Sometimes dreamers remember dreams from earlier in the night, but
in most cases the dreams that are remembered are those that occur closest
to waking.
Researchers know, however, that dreaming occurs during
all four to seven sessions of REM sleep. They know this through their work
with volunteers who agree to be awakened during REM sleep. Those awakened
during REM sleep generally provide very vivid descriptions of those
dreams, as do those who awaken naturally during a particularly vivid,
intense or frightening dream.
cycle, and
the function of dream sleep within this sleep cycle. Dream
sleep is a distinct part of the sleep cycle, different in almost every way
from other types of sleep.