Table 2.
Differential diagnosis of recurrent isolated sleep paralysis from other conditionsa
| Condition | Differences from sleep paralysis |
|---|---|
| Exploding Head Syndrome (EHS) | EHS and SP are both potentially frightening parasomnias. The auditory (bangs, explosions) and visual (light flashes) hallucinations of EHS are usually briefer (often 1 second or less) than SP hallucinations, always loud/jarring, and undifferentiated (ie, not recognizable speech or part of a developed narrative); no paralysis occurs during EHS and conscious awareness of surroundings is absent |
| Nightmare disorder (ND) | ND and SP are both REM-based parasomnias. The conscious awareness of one’s surroundings and atonia is missing in ND; dream imagery, though common in SP, need not be present for diagnosis, but is required for ND; unlike ND, SP hallucinations are not always negatively valenced (but usually are) |
| Sleep/night terrors (STs) | STs and SP are both potentially frightening parasomnias. STs are non-REM based and lack awareness to surroundings; dream imagery in STs, if present at all, is quite impoverished; characteristic screams during STs are not possible during SP; attempts to comfort SP sufferers often result in a resolution of the episode, whereas this is not the case with STs |
| Nocturnal panic attacks (NPAs) | NPAs and SP both involve fear and acute distress. NPAs lack paralysis and dream imagery (ie, they are non-REM based); NPAs are unexpected, acute, and scary, whereas fear in SP is often secondary to the paralysis/hallucinations |
| Posttraumatic stress disorder (PTSD) | PTSD and SP often include scary imagery and anxiety. PTSD flashbacks, though often containing vivid and frightening images, are not usually just limited to sleep–wake transitions; any hypervigilance in SP is not as pervasive as in PTSD; paralysis in PTSD is usually a subjective feeling or misperception during flashbacks, not an actual physical limitation; images during flashbacks are related to the offending trauma(s) |
| Schizophrenia and other psychotic disorders | Psychotic disorders and SP often share disturbing and unwanted hallucinations. However, hallucinations during SP are limited to sleep–wake transitions and gross reality testing is otherwise intact |
Note:
a
Adapted from Sharpless and Doghramji.2
Abbreviations: SP, sleep paralysis; REM, rapid eye movement.