The article repeatedly gives the impression of an abrupt change, by using words like 'switched' and 'stopped', but the description used later makes it sound like a more 'normal', gradual process.

she gradually spoke more quietly or moved less and less until she drifted into unconsciousness.

That part of the process sounds very similar to someone undergoing anesthesia, or simply falling asleep. Though there are obvious differences.

So maybe that's what it feels like? Some people remember the feeling of going under, but maybe not the last few seconds of it.