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 |
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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 |
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Vocalizations | Yes | Yes | Marked (screaming or crying) | Yes | Marked | Slight (moaning or groaning) | Sometimes |
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Getting out of bed | Rare | Usual | Sometimes | Always (food seeking) | Yes | No | No |
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Responsiveness on awakening | Decreased | Decreased | Decreased | Decreased | Responsive | Responsive | Responsive |
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Autonomic activity | Normal | Normal | Increased | Normal | No | No | Yes |
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Post-event confusion | Yes | Yes | Yes | Yes | No | No | No |
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Prevalence | 4.2% (10) | 1%–4% in adults, 80% of adults have sleep walked as children (10) | 1%–2% in adults (10) | Unknown; estimated to be 1%–5% in general population but higher among patients with eating disorders; 2–4 times more common among women (4) | Unknown; estimated to be 0.38% in the general population and 0.5% among elderly people; about 33% of patients with newly diagnosed Parkinson Disease (1); more common among men | Unknown. 15%–40% has been reported among students under 30 years for at least one episode (1) and 1%–10% of the population for multiple episodes (4) | 5%–8% of adults; (4) more common among women |
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Amnesia of event | Yes | Yes | Yes | Variable | No | No | No |
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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 |
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Family history of parasomnias | Yes | Yes | Yes | Yes | Occasionally | Yes | Yes; twin studies suggest a genetic predisposition and co-occurrence with other parasomnias (1) |