Epidemiology & Clinic of Parasomnia

Epidemiology of Parasomnias in the U.S. General Population

The prevalence rates of parasomnias were investigated in a sample of 15,927 individuals aged between 18 and 102 years. This sample is representative of the U.S. general population.

Sleepwalking was reported by 3.6% of the sample but sleepwalking occurring at least once a week was only at 0.2%. Confusional arousals were more common at 10% but weekly occurrence was reported only by 0.9% of the sample. Similarly, violent behaviors during sleep were observed in 2.7% of the sample but episodes occurring at least once per week were found in 0.7%. Sleep paralysis was frequent with 11.7% reporting having experienced episodes of paralysis in the previous year; 1.9% reported at least one episode of paralysis per week. Only violent behaviors during sleep were significantly associated with sex; men reporting more often these behaviors than women.

Parasomnias significantly decreased with age. Circadian Rhythm Sleep Disorders, Obstructive Sleep Apnea Syndrome and, to a lesser extent, Insomnia Disorders are strongly associated with parasomnias. Among psychotropic drugs, SSRI and tricyclic antidepressants are more frequently associated with parasomnia than other types of psychotropics.

Prevalence and Risk Factors of Parasomnias In Asia

Prevalence and risk factors associated with parasomnias in Asian adult population were seldom studied. Prevalence of most parasomnias is unknown in Asian countries.

Our epidemiological study examines the prevalence of parasomnias in the Korean general population using a representative sample of 2,537 individuals aged 15 years and older and a fuzzy logic Expert System (Sleep-EVAL).

Reports of sleepwalking episodes, confusional arousals and violent behaviors during sleep were very low with a respective prevalence in the past year of 0.9%, 1.0% and 0.9%. On the other hand, sleep paralysis and nightmares were common with at least monthly occurrence at 3.1% and 3.3% respectively. Only confusional arousals and violent behaviors during sleep were associated with the presence of an organic disease. Hypnotic and anxiolytic medication intake were not associated with any of these parasomnias. Antidepressant medication intake, however, was associated with at least a 10-fold increase in the risk of having sleepwalking, confusional arousals, sleep paralysis, nightmares or violent behaviors during sleep.

Sleepwalking, confusional arousals and violent behaviors during sleep appear to have lower prevalences in Korea than what was reported in European and North America countries. However, associated factors are similar.

A video presentation of Parasomnias

Approximately 20 videos of abnormal events during sleep will be presented with a differential diagnosis of the behavior so participants can make a choice of the correct diagnosis. The presentation is designed for an ARS to be used to record participants selections.

Parasomnias in Children: A Virtually Unexplored Area of Sleep

Pediatric parasomnias comprise a wide variety of different confounding behaviors during sleep. American Academy of Sleep Medicine defines parasomnias as "undesirable physical events or experiences that occur during entry into sleep, within sleep or during arousal from sleep". These events encompass abnormal sleep related movements, behaviors, emotions, perceptions, dreaming and autonomic nervous system functioning. Following the International Classification of Sleep Disorders (ICSD-2), they are subdivided into three groups:

  1. disorders of arousal (from NREM sleep);
  2. parasomnias usually associated with REM sleep, such as nightmare disorder or RBD;
  3. other parasomnias, e.g., enuresis.

The mechanisms underlying any of the parasomnia categories remain unclear. However, sleep perturbations that are currently categorized under this classification are multiple and may or may not be mediated by similar processes. Furthermore, it remains unclear whether parasomnias in children have any adverse implications on daytime functioning, even though some of the initial observations in this direction would tend to support such an association. The clustering of parasomnias in families and twins would further imply a strong genetic component, the latter however, has not been thoroughly explored. Notwithstanding, sleep terrors were found to have a possible autosomal dominant inheritance in a 3-generation family.

Similarly, the prevalence of sleep terrors and sleepwalking in first degree relatives of individuals with sleep terrors is 10 times greater than in the general population, with a 60 % chance estimate for a child to be affected if both parents are affected. Population-based studies of monozygotic and dizygotic twins suggest that genetic factors are involved in 65 % of cases of sleepwalking.

Beside genetic influences, other contributing triggering factors have been identified for parasomnias, such as younger age, sleep deprivation, irregular sleep schedules, emotional stress, fever, and co-existing sleep disorders, such as obstructive sleep apnea and periodic limb movements in sleep. Treatment is usually not necessary, except in extreme cases.

Parasomnias in Older Adults

Sleep disturbances in older adults are common and are associated with decreased quality of life and increased morbidity and mortality.

The parasomnias, disorders of arousal, partial arousal, and sleep-stage transition are both common and poorly understood in older adults. Some parasomnias such as REM sleep behavior disorder (RBD) and restless leg syndrome (RLS) are fairly well characterized and known to increase in prevalence with advancing age.

Of particular concern is the potential adverse impact of parasomnias such as RLS in the growing proportion of the older adult population who have a dementing disorder such as Alzheimer's disease (AD), who often have only a limited ability to express any RLS symptoms they are experiencing. The presence of occult RLS in such patients has been proposed as a possible explanation for the agitated behaviors that often occur in the pre-bedtime hours, historically and anecdotally described as "sundowning." This may particularly be the case in more impaired AD patients in long-term care settings.

The evidence supporting this possibility and the implications for its effective treatment will be reviewed.