I don't think I would stop single handing. It is easy to ponder all of the horrible situations you could be in when something like this happens, standing on deck changing a sail, up on the mast changing a light, etc, but how much time do you actually spend doing those things, and how likely is it that you'll have a seizure at that exact moment ? Maybe a good thought experiment is to put a watch in your pocket and set the alarm(s) on it to go off at different times during the day, then when the alarm goes off consider - how likely is it that you would have died if you had a seizure at the exact time that alarm goes off ? I bet the answer is, not very likely, except for one situation, and that situation is driving an automobile. I think the chances of that alarm going off when you're making some critical life and death decision on a boat, or standing on the edge of the boat taking a pee without a harness
, are probably pretty unlikely. No, the alarm probably goes off when you're sitting there drinking a cold beverage considering nothing important at all, and if you were to pass out at that moment chances are you'd wake up sitting in the same place covered in cold beverage.