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Parasomnias
by
Helen Driver, Phd, RPsgT
Parasomnias
can be described as “strange things that go bump in the
night”.
They
are a group of acute, undesirable, episodic physical phenomena
that usually occur during sleep, or are exaggerated by sleep.
Even though parasomnias occur during different stages of
sleep and at different times during the night they are characterized
by partial arousals before, during, or after the event.
Most parasomnias are precipitated or perpetuated by stress,
and an interaction between biological and psychological
factors is presumed in many cases.
There
are three different types of parasomnias, one being those
that occur during deep sleep
or slow wave sleep (SWS).
Slow wave
sleep associated parasomnias are also known as disorders of
arousal.
Sleep walking (somnambulism) and night terrors (“pavor
nocturnus” in children and “incubus” in adults) are
in the group of SWS parasomnias. Slow wave sleep is nonREM
sleep (stages 3 and 4), and is the deepest sleep occurring
mostly during the first three hours of the night. Patients
who’s sleep is disturbed, rather than becoming fully awake
from SWS, enter a state of confusion and disorientation.
In association with the partial arousal, heart rate and
breathing increase.
Both sleep walking and night terrors are described as “immaturities
of the central nervous system” in children, typically between
4-12 years of age, which they grow out of; in adults they
are thought to be more indicative of psychopathology. Recall
of these events is usually lacking or poor, and a typical
episode lasts about 6 minutes but may range from a few seconds
up to 30 minutes. Predisposing factors include a genetic
component, sleep deprivation, irregular sleep-wake schedules,
fever, certain medications including cardiac drugs and sedatives.
Sleep
walking
During sleep walking vision seems to remain intact; coordination
of the central nervous system is maintained to some extent,
although accidental injuries have been reported (see photograph).
An episode can last from minutes to an hour. More than
one episode a night is rare, as is the likelihood of complex
manoeuvres.
It is particularly important that these patients are instructed
to sleep in a safe environment. Patients should be advised
to avoid sleep deprivation (long drives at night, or shift
work) or other circumstances that might make them excessively
sleepy.
Night
terrors
Night terrors usually start with a terrifying scream, increased
heart and breathing rates, sweating and a frightened expression.
They last from one to several minutes, and should be distinguished
from nightmares. Nightmares are parasomnias associated with
REM sleep and occur during the middle and last third of
sleep, when REM periods are more abundant and intense; patients
arouse easily and quickly. In contrast to nightmares, which
are frightening dreams with vivid recall, patients rarely
remember specific details of a night terror.
Particularly in children experiencing night terrors, reassuring
the parents and the child should be the first line of treatment.
A regular bedtime routine that permits sufficient sleep
often leads to improvement in children. Many simple parasomnias
improve with improved sleep hygiene, and in adults particularly
decreased alcohol and caffeine consumption.
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Features
of sleep walking and night terrors
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·
They occur primarily in the first third
of sleep when slow wave sleep is most prominent
·
Slow wave sleep (SWS) is deep sleep: it
is difficult to wake the patient
·
Patients rarely remember specific details
of the event
·
Conditions in which there are higher levels
of SWS tend to increase the frequency of these parasomnias
(for example, sleep deprivation, shift work, and alcohol
consumption)
·
Medical disorders associated with these
parasomnias include obstructive sleep apnoea syndrome,
migraine and epileptic seizures
·
They are more common in children (the
onset is usually before the age of 10 years). Children
have more SWS than adults
·
One person may have more than one form
of parasomnia. There may be a common genetic and neurophysiological
substrate in somnambulism and night terrors
·
These parasomnias may occur in response
to stress or anxiety and may be more common when sleep
schedules are irregular. |
Continue
Reading (Parasomias Part II)
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