Table 1: Summary of Features of Sleep Paralysis 

Description

    A. Core Features (definitive)
      1. subjective impression of wakefulness
      2. immobility
        • variously perceived (paralysis, restraint, fear of moving)
        • veridical perception of actual environment 
    B. HHEs - hynagogic and hypnopompic experiences
 
                        1. Secondary features (reported regularly) 
 
  • visual control (very common - probably diagnostic except some people may be afraid to try to open their eyes)
            1. eyes open and close
            2. visual scanning intact
  • fear - terror (very common) of:
            1. presence
            2. death
            3. harm
            4. mental or neurological disorder
  • feeling of presence - (common) -- usually threatening or evil or occasionally ugly. It may be human, animal, or neither, or even some combination, or undecidable. May be:
            1. watching
            2. attacking
            3. speaking
  • feelings of pressure on chest or other body part (common)
            1. movement under pressure being pushed
            2. may be painful (rarely)
            3. choking or smothering sensations (may be separate from, or a variation on, chest pressure)
  • numinous quality (common)
  • auditory hallucinations (fairly common) - usually soft and indistinct
            1. footsteps (most common auditory feature) - often shuffling
            2. breathing
  • visual hallucinations (moderately common - slightly less than auditory) difficult to describe - have ethereal "as if" quality
            1. ghostly humanoid form in outline
            2. usually dark or gray
            3. often only a face or "mask"
            4. eyes are most common, and often only, distinct feature
            5. may undergo transformations and movement
  • floating or feelings of being lifted up (fairly common) 
2. Tertiary Features -- Occasional experiences 
  • supine position
  • Choking, smothering (may be interpreted as attack of presence or associated with pressure on chest)
  • moving covers being dragged off the bed
  • olfactory hallucinations(rare) 
3. Other features-- Rare 
  • continuity does not have shifting scenes of a dream - much more like the continuity of conscious experience
  • derealization depersonalization -- distortions of body image dissociation of modalities - kinesthetic and visual, pressure down and floating and visual
  • out-of-body experiences
  • tingling or vibrating sensations
 

Frequency and Distribution

 
    1. Overall: 25-30 %
    2. No sex differences
    3. Pattern or Recurrence
      1. Once only or once and occasionally, with intervals of months or years (most common)
      2. one or more "runs" of frequent attacks lasting one or two weeks (sometimes)
      3. fairly chronic attacks of a long period (infrequent)