Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
1
Is any of this happening now?
Call 911
Emergency help is appropriate if weakness continues after you are fully awake, affects one side of the body, or occurs with trouble speaking, facial drooping, severe chest pain, ongoing breathing difficulty, fainting, or prolonged confusion.
These are not usual features of sleep paralysis and may indicate another medical problem.
Other emergency signs, for anyone
Someone who is struggling to breathe, gasping, choking, or cannot get words out
Someone who has chest pain, tightness or pressure lasting more than a few minutes
Someone who has sudden weakness or drooping on one side of the face or body, slurred speech, or sudden confusion
Someone who is unconscious, or cannot be woken
Someone who is bleeding heavily and it will not stop with firm pressure
Someone who has had a seizure that will not stop, or does not wake up afterwards
Someone who has lips or skin that look pale, blue, grey or blotchy
Someone who you believe has taken an overdose or swallowed something poisonous
2
Does any of this apply?
Book an appointment
Arrange a routine appointment if episodes are frequent, increasingly distressing, or making you afraid to sleep.
Assessment is also appropriate if sleep disruption is affecting your mood, concentration, school, work, or daily activities.
Seek routine medical assessment if you also have:
Strong daytime sleepiness despite enough time in bed
Sudden sleep attacks
Sudden muscle weakness triggered by emotion
Loud snoring, gasping, or witnessed breathing pauses
Unusual movements, injuries, confusion, or loss of bladder control during events
Hallucinations when you are fully awake and not near sleep
The article also says
Typical sleep paralysis is not an emergency.
Every sign above is quoted from the sofidex article on Sleep paralysis. If you are not sure, err upward — it is always reasonable to be checked.