Characteristics of parasomnias
| Characteristic | Nonrapid eye movement parasomnia | Rapid eye movement parasomnia | |||||
|---|---|---|---|---|---|---|---|
| Confusional arousal | Sleepwalking | Sleep terrors | Sleep-related eating disorder | REM sleep behaviour disorder | Sleep paralysis | Nightmare disorder | |
| Emerges from | Stages II, III and IV* | Stages III and IV | Stages III and IV | Stages II, III and IV | REM sleep | REM sleep | REM sleep |
| Time of night | Anytime during sleep | First third of sleep | First third of sleep | Anytime during sleep | Anytime but most frequently last third of sleep | Anytime | Anytime but most frequently last third of sleep |
| Vocalizations | Yes | Yes | Marked (screaming or crying) | Yes | Marked | Slight (moaning or groaning) | Sometimes |
| Getting out of bed | Rare | Usual | Sometimes | Always (food seeking) | Yes | No | No |
| Responsiveness on awakening | Decreased | Decreased | Decreased | Decreased | Responsive | Responsive | Responsive |
| Autonomic activity | Normal | Normal | Increased | Normal | No | No | Yes |
| Post-event confusion | Yes | Yes | Yes | Yes | No | No | No |
| Prevalence | 4.2%10 | 1%–4% in adults, 80% of adults have sleep walked as children10 | 1%–2% in adults10 | Unknown; estimated to be 1%–5% in general population but higher among patients with eating disorders; 2–4 times more common among women4 | Unknown; 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 episodes4 | 5%–8% of adults;4 more common among women |
| Amnesia of event | Yes | Yes | Yes | Variable | No | No | No |
| Injury risk | Low if undisturbed | Low if undisturbed; may strike out if disturbed or intoxicated | More common; may injure self trying to escape; may strike out if disturbed or intoxicated | Self-injury from food preparation (cuts, burns, poisoning) | May injure self or partner as part of dream enactment | None | None |
| Family history of parasomnias | Yes | Yes | Yes | Yes | Occasionally | Yes | Yes; 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