Authored by MCN Neurologists

Parasomnias are a group of benign but alarming disorders that occur exclusively associated with sleep. They can be complex or simple in appearance and each parasomnia has unique characteristics and patterns, which will be discussed individually.

Night terrors typically occur in toddlers and young children, but can occur in other age groups as well, and are characterized by “waking up” several hours after falling asleep, crying uncontrollably as if in pain or terrified.  They are inconsolable and while their eyes are open and are able to move normally, they are not appropriately responsive to questions, requests or commands.  The entire episode can last up to several hours, but more typically lasts up to one-half hour, after which they will fall back asleep. In the morning, there is no recollection of the episode (although the parents cannot forget it!).  Night terrors differ from nightmares in that there is no “bad dream” associated with the event.  It is a harmless disorder (except for the anxiety and lack of sleep in the parents) and does not require treatment, per se.  Night terrors usually resolve spontaneously after several years but may be precipitated by stress or illness.

Sleepwalking (somnambulism) and talking in one’s sleep (somniloquy), the most familiar parasomnias, consist of semi-purposeful walking or talking and other activities (such as eating) while remaining asleep.  The speech may not make any sense in relation to environmental circumstances and conditions, but sometimes they can carry on a simple conversation.  These disorders are harmless in themselves, but concerns about injuries or entering unsafe environments while sleepwalking, may necessitate treatment.  Likewise, if coupled with an eating behavior, intervention may be necessary.

Nocturnal myoclonus is the sudden jerking of a limb or the entire body, primarily occurring when falling asleep or waking up, but can occur at other times during the night.  At times the myoclonic jerks may be quite violent or repetitive.  The majority of nocturnal myoclonus activity is normal and does not require any intervention.  Children and adults may have a variety of sleep movements, including rocking, turning, or head banging, all of which are benign.

Periodic leg movements of sleep are, as their name implies, leg movements that occur frequently or nearly constantly during sleep. While not bothersome to the individual, they will frequently keep the bed partner awake throughout the night. They can occur in association with daytime restless leg syndrome and more often occur in adults than children.

While not technically classified as parasomnias, sleep paralysis and hypnagogic hallucinations are benign, but concerning events that occur when falling asleep or awakening.  REM (rapid eye movement) sleep behavioral disorder occurs while the individual is asleep and consists of acting out the content of the dream in real life, at times quite violently.  To understand these disorders, a brief explanation of the physiology of REM, or dreaming, sleep is necessary.  REM, or dreaming sleep, is necessary for being adequately rested in the morning. During normal REM sleep, special circuits in the brain completely inhibit all motor activity (all sleep movement occurs during non-REM sleep) except breathing and eye movements. 

Sleep paralysis occurs when there is abnormal persistence of the motor inhibition, but arousal to normal wakefulness.  The sensation of being awake, but unable to have voluntary movement, is alarming, but brief (less than a few minutes) and completely benign.

Hypnagogic hallucination consists of the intrusion of sensory perceptions from dreams involving hearing, smell, vision or touch, while physically awake.  Hypnagogic hallucinations can also be quite alarming, but are also benign.  While hypnagogic hallucinations and sleep paralysis can occur occasionally in otherwise healthy individuals, they most commonly occur associated with narcolepsy.

REM sleep disorder occurs when people dream, but there is failure of motor inhibition.  Therefore, people will act out their dreams, occasionally with violent or aggressive behavior, and the individual can injure themselves or their bedmates.  The activity stops when awakened.  An increased incidence of REM sleep disorder has been associated with Parkinson's disease.

What to Expect at Your Doctor Visit

While parasomnias are benign and usually harmless, it is necessary to be certain that other underlying neurologic problems are not mimicking parasomnias.  These would include seizures, paroxysmal nocturnal dystonia and other sleep disorders.  The neurologist will take a thorough history of the episode, including a detailed description, timing, duration and any other associated symptoms that occur.  A videotape of one of the episodes is very helpful in confirming the diagnosis.  Blood tests and a regular or sleep deprived electroencephalogram (brainwave test) might be necessary.  Rarely, an overnight sleep study or video electroencephalogram may be performed if the diagnosis remains in doubt.  MRI scan is not helpful, except in rare circumstances.

Treatment And Prevention of Parasomnias

Parasomnias are generally harmless and benign events from the patient's standpoint and do not generally require any medical treatment.  Good sleep hygiene, with regular sleep hours, avoidance of caffeine and alcohol and stress reduction, can be very helpful in reducing the frequency and severity of the parasomnias.  Alarms, deadbolt locks on doors and other safety measures can be helpful.  In extreme cases, medications, such as imipramine or carnets of Pam, can be used to control excessively bothersome parasomnias.

January 1, 2010

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