Parasomnias are sleep disorders that include unusual behavior or perceptions.

Among other things, they include nightmares, sleep paralysis, night terrors, sleepwalking (sonambulism), sleep talking (somniloquy), sleep sex, bedwetting (enuresis), restless legs syndrome and teeth grinding (bruxism). In order to understand parasomnia, it helps to understand the different stages of sleep.


Scientists divide human sleep into two major categories. Those are NREM
or non-rapid eye movement and REM or rapid eye movement. These stages
are relatively easy to spot, just by looking at a person’s eyes.

In NREM there is little or no movement of the eye under the lid. In
REM, there is rapid eye movement, typically from side to side. It’s
almost as if a person is watching what’s going on in their dreams.

In healthy individuals REM accounts for 20-25% of total sleep time.
During that period, a person is practically paralyzed, normally. They
are unable to act out what’s going on in their dreams, which is a good
thing, as they can harm themselves otherwise.

Parasomnias - Man Walking on Beach Under Blue MoonlightPhoto: Barun Patro
Parasomnias - Man Walking on Beach Under Blue MoonlightPhoto: Barun Patro

NREM accounts for the majority of sleep time and is divided into
three stages, N1, N2 and N3. An EEG is necessary to determine which
stage of NREM a person is actually in. The brain waves differ.

For example, in stage N1 the transition from alpha waves, which the
brain emits when fully awake, to theta waves is made. The stage is
sometimes accompanied by a sensation of falling or other hallucinations,
as well as jerking muscles, those are examples of parasomnias. They
may be troublesome, but are not usually disruptive.

About 45-55% of a person’s sleep time is spent in stage N2, but if
chronically deprived of N3 and/or REM, a person may suffer from symptoms of sleep deprivation. N3 is also described as “delta” sleep, because of the delta waves emitted by the brain during that stage.

Parasomnias can occur during any stage of sleep. The majority occur
during stage N3. Night terrors, bedwetting, sleepwalking and talking,
for example, typically occur in the N3 stage.

A specific kind of parasomnia is referred to as REM Sleep Behavior
Disorder or RBD. In people that suffer from RBD, the normal muscle
paralysis that occurs during REM sleep is absent, which means that
people can and do act out their dreams.

The results are more than troublesome. Mild and serious injuries can
occur, including bruises and broken bones. People that suffer from
the problem must often take self-protective measures, such as tethering
themselves to the bed or barricading themselves into their rooms. The
tasks that people can perform during RBD are surprising.

There are two types of RBD; acute and chronic. The most common cause
of acute RBD is prescription medications. Anti-depressants, for
example, can cause RBD.

Chronic RBD, on the other hand, is associated with neurological
disorders, such as Parkinson’s disease. People with narcolepsy, a
different kind of sleep disorder in which people fall asleep at
inappropriate times, often suffer from RBD too.

Treating sleep disorders is difficult. There is reason to believe
that nutritional deficiencies and genetics play a role. Sometimes,
correcting the nutritional deficiency resolves the problem. For
example, restless legs syndrome is often caused by a magnesium

Parasomnias can be troubling for the individuals that suffer from
them and for their bed partners. The best advice is to attempt to find
the cause and adopt an appropriate treatment plan.

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