Table 1:

Characteristics of parasomnias

CharacteristicNonrapid eye movement parasomniaRapid eye movement parasomnia
Confusional arousalSleepwalkingSleep terrorsSleep-related eating disorderREM sleep behaviour disorderSleep paralysisNightmare disorder
Emerges fromStages II, III and IV*Stages III and IVStages III and IVStages II, III and IVREM sleepREM sleepREM sleep
Time of nightAnytime during sleepFirst third of sleepFirst third of sleepAnytime during sleepAnytime but most frequently last third of sleepAnytimeAnytime but most frequently last third of sleep
VocalizationsYesYesMarked (screaming or crying)YesMarkedSlight (moaning or groaning)Sometimes
Getting out of bedRareUsualSometimesAlways (food seeking)YesNoNo
Responsiveness on awakeningDecreasedDecreasedDecreasedDecreasedResponsiveResponsiveResponsive
Autonomic activityNormalNormalIncreasedNormalNoNoYes
Post-event confusionYesYesYesYesNoNoNo
Prevalence4.2%101%–4% in adults, 80% of adults have sleep walked as children101%–2% in adults10Unknown; estimated to be 1%–5% in general population but higher among patients with eating disorders; 2–4 times more common among women4Unknown; estimated to be 0.38% in the general population and 0.5% among elderly people;
about 33% of patients with newly diagnosed Parkinson Disease1; more common among men
Unknown. 15%–40% has been reported among students under 30 years for at least one episode1 and 1%–10% of the population for multiple episodes45%–8% of adults;4 more common among women
Amnesia of eventYesYesYesVariableNoNoNo
Injury riskLow if undisturbedLow if undisturbed; may strike out if disturbed or intoxicatedMore common; may injure self trying to escape; may strike out if disturbed or intoxicatedSelf-injury from food preparation (cuts, burns, poisoning)May injure self or partner as part of dream enactmentNoneNone
Family history of parasomniasYesYesYesYesOccasionallyYesYes; twin studies suggest a genetic predisposition and co-occurrence with other parasomnias1
  • Note: REM = rapid eye movement.

  • * The scoring of sleep has changed recently with Stage II sleep being renamed N2, and stages III and IV being named N3. Because most clinicians are familiar with the old staging nomenclature, this is what we have used in this review.7