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 your child has serious trouble breathing, develops blue or grey lips or skin, has a serious injury, or cannot be roused after the event.
Emergency help is also appropriate for prolonged or repeated seizure-like activity, such as rhythmic jerking or stiffening with loss of responsiveness.
It is not usually necessary to seek emergency care.
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 medical assessment if movements are highly repetitive each time, episodes occur many times in one night, or your child remains unusually confused or unwell after waking.
These features do not prove that seizures are occurring, but they deserve assessment.
3
Does any of this apply?
Book an appointment
Arrange a routine appointment if the episodes:
Happen often, become more intense, or regularly disrupt family sleep
Cause daytime sleepiness, poor concentration, or behaviour changes
Begin for the first time in an older child or continue into adulthood
Lead to repeated falls, wandering, or minor injuries
Include loud snoring, gasping, choking, or pauses in breathing
Started after a new medicine or dose change
Look different from typical night terrors or remain difficult to identify
The article also says
During a typical night terror without these warning signs, the priority is quiet supervision and injury prevention.
Every sign above is quoted from the sofidex article on Night terrors in children. If you are not sure, err upward — it is always reasonable to be checked.