I've done this before. Works well.Should have chucked a 'I have been known on occasion to become disoriented, pass out and have seizures from flickering lights. Please turn it off, or prepare for me to make on
hell of a disruption to your exam"
Just say you are prone to lose consciousness around flickering light and shit and they have to turn it off or you will need their supervisor number ao you can report them to BOS. Say it nicely though.