Parasomnias are disorders of arousal or the interface between sleep and waking. Think of them as abnormal arousals. Parasomnias may be induced or exacerbated by sleep but they are not disorders of the sleep stages as dyssomnias are.
Parasomnias include movements or behaviors that may impair sleep continuance, associated with sleep, sleep stages, or partial arousals from sleep. Parasomnias can be divided into four groups of disorders
These parasomnias encompass arousals with abnormal motor activity (i.e. uncontrollable violent behavior), behavioral experiences (i.e. sleep walking), or sensory experiences (i.e. dreamlike hallucinations). Parasomnias are more common in children; frequency decreases with age; the reported prevalence of parasomnias is approximately 4% in the adult population.
Catathrenia (groaning during sleep) is sometimes called a parasmonia, although it could also be considered a feature of sleep-disordered breathing.
Trichotillomania - the impluse control disorder that causes people to pull their own hair out - has been proposed as a parasomnia - when the patient does it while asleep.
Although these undesirable physical and behavioral incidents and actions during sleep can be worrying and occasionally hazardous to the sleeper, you should remember that frequent or particularly dramatic parasomnias are diagnosable and treatable in most cases. The effective therapy in most cases is medication with long- or medium-acting benzodiazepine, such as clonazepam, taken at night before sleep.
Hallucinations – Many people occasionally experience a hallucination in conjunction with sleep (39%), although for half of those people it happens less than once a month. Hallucinations when falling asleep (hypnagogic hallucinations) are four times more common than when waking up (hypnopompic hallucinations).
Growing Pains? - An intriguing idea is that growing pains are a form of sleep disorder. Like parasomnias, they are relatively common in pre-school children and there appears to be a correlation with night terrors.
Parasomnia occur more frequently in kids than in adults. Indeed, over 80% of preschool-age children experience parasomnia events. Some pyschologists associate parasmonias in young (preschool) children with separation anxiety. There is a genetic predisposition for parasomnias, but specific genes and how they interact with the environment are not known.
The prevalence of parasomnias is estimated at 4% in the general adult population. Epidemiology studies estimate the occurrence of parasomnias according to parameters as age, gender and the co-morbidity of existing medical conditions. The findings in these epidemiology studies show an even higher prevalence in association to these parameters.
Treatment of Parasmonias
Over the years scientists and doctors have developed treatments for parasomnias - both pharmacological and behavioral. The treatments are hit and miss; they don't always work and it is not clear than have to work. Sometimes doctors feel no treatment is often preferable to available therapies because the symptoms are not severe, the disorders do not get worse or lead to other disorders, and the parasomnias that disappear over time are considered childhood issues because kids love them when they grow up. Further the science underlying the treatment of parasomnia is not as robust as some other medical treatments, perhaps because low incidences of the disorders means small sample sizes in trials and studies.
Epileptic seizures look like parasomnias sometimes. There is a wide range of seizure activity and symptoms, and they can look like disorders of arousal from REM sleep. Doctors have to distinguish between the two during diagnosis.
A polysomnogram can differentiate between the two. But there does seem to be a connection, if only through genetics. If a person has nocturnal frontal lobe epilepsy his or her family members are more likely to have parasomnias. Impairment in the cholinergic system seems to be behind both.
"O Sleep, rest of all things, mildest of the gods, balm of the soul..."
(Iris to Hypnos. Ovid, Metamorphoses)