Sleep
is a dynamic process consisting of two basic states:
Rapid Eye
Movement (REM) and non-Rapid Eye Movement (non-REM) sleep.
-These two basic states are as different
from each other as sleep differs from wakefulness!
-Non-REM
sleep is divided into four stages, numbered 1 through 4 (1=the
lightest--drowsiness, and 4=the soundest). In all these non-REM
states, the brain is relatively inactive and the body is relatively
active (our muscle tone is maintained). "Active body, inactive
brain"!
-In
contrast, REM sleep is just the opposite in some respects. Our
brain is very active--this state is that from which we recall our
most vivid dreams. To keep us from acting out those dreams (which
could be dangerous particularly when our dreams are violent) we
become limp and paralyzed. Of course, if we stay asleep, we don't
even know that we become paralyzed. "Active brain, inactive
body"!
-We
must cycle back and forth between these two types of sleep repeatedly
during any given night of sleep--usually some four or five times.
Normal people start with progressively deeper stages of non-REM
sleep, and then have their first period of REM sleep only after
some ninety minutes of non-REM sleep have occurred..after
which they have more non-REM sleep, followed by yet another
REM period. This cycling between non-REM and REM sleep continues
until final awakening. Each successive REM period tends to
be longer than those that preceded it, so we get most of
our REM sleep during the last part of our sleep. In contrast,
most of our deeper stages of non-REM sleep occur during the
first third of the night.
REM-related symptoms can
occur for two basic reasons:
-REM
sleep occurs too early.
-The
component parts of REM sleep (the vivid dreaming and paralysis)
don't stay "glued together" as
they should--and parts of REM sleep intrude into wakefulness,
where they don't belong!
Although
the consequences are usually harmless, they often are very
frightening. For example: while it's not so bad to be paralyzed
in sleep when you don't even know about it, to experience
sudden paralysis when awake is "the pits"!
What
are some REM-related symptoms?
-REM
sleep occurs too early.
Vivid
dreaming in brief naps, or the immediate onset of dreaming after
falling asleep. When these symptoms truly reflect the premature
onset of REM sleep, they can represent symptoms of
such disorders as narcolepsy and sleep
apnea, and
can also be caused by withdrawal from medicines or
other substances, such as alcohol, that suppress REM
sleep. Withdrawal of "REM suppressants" can be followed by a "REM rebound".
-Dream
fragments occur at times when the person is not fully asleep!
The
individual may begin watching a vivid dream while still
hearing his or her surroundings, or instead hear the "sound track of a dream" when
not fully asleep. In other cases, the person may feel
things that aren't there (rain on one's forehead, the sensation
of a rat running across one's leg, etc.). These hallucinations
are called hypnogogic hallucinations when
they precede sleep onset and hypnopompic hallucinations
when they occur immediately after awakening. They often seem real
to the point of causing terror or fears that one is losing
one's mind. They can arise from narcolepsy,
withdrawal from REM suppressants, and occasionally from
such other causes as sleep
apnea and severe
sleep deprivation.
-The
paralysis of REM sleep intrudes into wakefulness--which can cause
two different problems:
-Sleep
paralysis. The person suddenly notes complete inability to move
or call out for help either when first dozing off or upon first
awakening. The sensation is much like being buried alive! However,
it is transient, harmless and can be broken by being touched
(which is small comfort when one cannot call out for
help!). This phenomenon can arise from the same causes as hypnagogic
hallucinations. Sleep paralysis also can occur as a rare
event in otherwise normal individuals.
-Cataplexy.
This is the only symptom that is diagnostic of narcolepsy in
sleepy individuals (although not all patients with narcolepsy
develop cataplexy). Cataplexy refers to triggering of
the limp paralysis that should only occur in REM sleep
instead by emotions during wakefulness. Upon experiencing
a humorous event, laughing, encountering an old friend
or when experiencing other emotions as excitement during
athletic competition or anger, the person with cataplexy
experiences waves of muscle weakness that may
cause sagging of the face with inability to speak, bobbing
of the head, dropping things, or buckling of the knees.
In severe cases, the individual may even experience total
collapse with falling and complete paralysis, but with
maintained consciousness. The attack may last only seconds.
However, some seriously afflicted patients can remain
in a totally helpless state for a half-hour or longer.
While these attacks can be mistaken for blackouts or
seizures, they are simply the result of one component
part of REM sleep occurring at the wrong time.
-Paralysis
fails to develop in REM sleep when it should!
-The
consequence? The individual able to act out dreams, sometimes
with serious injury to self or others--particularly when the
dreams have a violent content. In some cases, the individual
may even attack his or her bed partner during dreams of struggling
with an intruder who has entered the home. Some deaths have resulted.
-This
condition, REM Behavior Disorder (RBD) has been described most
frequently in men over age 60, some of whom also demonstrate
other disorders of the brain such as later development of Parkinson's
disease. It is a neurologic, not a psychiatric disorder, and often
a potentially dangerous one that can and should be treated. It
sometimes can be triggered by sleep
apnea.
It also can occur in younger individuals and women,
some of whom will be found to have narcolepsy!
Drugs such as antidepressants and sleeping pills can
also be factors in triggering this condition. Treatment
is available and in fact, is often crucial since this
disorder can prove dangerous.
FOR MORE INFORMATION ON REM-RELATED DISORDERS,
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