Parasomnias are a heterogeneous group of sleep disorders that are not strictly speaking abnormalities or dysfunctions of the processes underlying sleep-wake states.

The American Classification of mental disorders (DSM-IV, American Psychiatric Association) recognizes only three parasomnias:

  • Nightmares,
  • Night terrors
  • and Sleepwalking.

There are, however, several other parasomnias identified in the International Classification of Sleep Disorders, for example:

  • REM sleep behavior disorder,
  • sleep paralysis,
  • confusional arousals,
  • sleep talking, and
  • sleep enuresis.

Most of these disorders are relatively frequent and benign in children and adolescents and disappear in early adulthood. The presence of some of these disorders in adults, such as night terrors, nightmares, or confusional arousals may be indicative of a more severe disorder.


Adults with night terrors exhibit a high level of anxiety, depression, obsessive-compulsive and phobic traits on personality questionnaires such as the MMPI. Furthermore, mental stress and specific life events have been reported to trigger or increase the frequency of night terror and sleepwalking episodes.


Nightmares in adults are associated with various psychiatric disorders (1). Continuous recurrent nightmares positively response to antidepressant medications in depressed individuals. Nightmares are also frequently observed in schizophrenic patients and acute schizophrenic episodes are often preceded of a period of frequent nightmares. Individuals with a posttraumatic stress disorder may also experience recurrent nightmares about the traumatic event. The common association of sleep and eating abnormalities in patients with former sexual abuse (and other traumas) leads to many misdiagnoses in general practice (and in specialist sleep clinics).


Confusional arousals appear to occur quite frequently in the general population, affecting mostly younger subjects regardless of their gender. The association between confusional arousals, mental disorders and OSAS is frequent. Furthermore, the high occurrence of confusional arousals in shift or night workers may increase the likelihood of inappropriate response by employees sleeping at work.


Recent studies in the general population have shown that violent behaviors during sleep are not so rare:

  • 2% of the British public have experienced such behaviors (2).
  • These individuals present more frequently anxiety and mood disorders (20% to 25%).


Sleep paralysis is a transient and generalized inability to move and speak that occur during the transitional period between sleep and wakefulness. Episodes vary from one to several minutes and are usually extremely distressing especially when they are accompanied with hypnagogic or hypnopompic hallucinations. Sleep paralysis occurs in 30 to 60% of narcoleptic patients. Epidemiological studies shown that 6.2% of the general population experienced at least one such episode in their lifetime. Moreover, sleep paralysis is often associated with a mental disorder. In some cases, anxiolytic medication may be responsible for this manifestation (3).


Other parasomnias are interesting because they cause fear to individuals presenting with them. They are also interesting because they are not well-known by the physicians.


  1. Ohayon MM, Morselli PL, Guilleminault C. Prevalence of nightmares and its relationship to psychopathology and daytime functioning in insomnia subjects. Sleep 1997; 20:340-8.
  2. Ohayon MM, Caulet M, Priest RG. Violent behaviour during sleep. J Clin Psychiatry 1997;58:369-76.
  3. Ohayon MM, Zulley J, Guilleminault C, Smirne S. Prevalence and pathological associations of sleep paralysis in the general population. Neurology 1999; 52: 1194-200.