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
Call emergency services if someone:
Has severe difficulty breathing while awake
Turns blue, gray, or unusually pale
Cannot be woken normally
Has breathing that does not restart
Develops chest pain or signs of stroke, such as facial drooping or sudden weakness
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
Is any of this happening?
Be seen today
Seek prompt advice if sleepiness is affecting driving, work, or other safety-sensitive activities.
Do not drive when sleepy.
If you become drowsy while driving, stop somewhere safe rather than trying to push through it.
3
Does any of this apply?
Book an appointment
Arrange a routine medical assessment if you have frequent loud snoring together with witnessed breathing pauses, gasping, morning headaches, or unexplained daytime sleepiness.
Assessment is also appropriate if a child regularly snores or has restless sleep with behavior, attention, or growth concerns.
Witnessing these events is a reason to arrange assessment, but it is not usually an emergency if normal breathing promptly returns and the person is otherwise well.
The article also says
The brief breathing pauses typical of OSA usually end with a gasp or partial awakening.
Every sign above is quoted from the sofidex article on Obstructive sleep apnea. If you are not sure, err upward — it is always reasonable to be checked.