If you find yourself unable to move or speak for a few seconds to minutes, while falling asleep or waking up, you may be having SP. Seeing, hearing and feeling things that are not there (sleep hallucinations) may also be present. People have reported a pressure sensation on their chest with a sense of being smothered (as if they will die), or may feel a spinning and floating sensation and have difficulty speaking during these spells.

SP is an intrusion of the muscle paralysis of REM sleep into wakefulness, and is likely to be seen for the first time during adolescence and early 20s.

If daytime sleepiness, sleep hallucinations and cataplexy are also present, SP may be a symptom of Narcolepsy. Recurrent isolated SP may also occur without other symptoms.