Then I woke up flat on my back on the floor.
Evidently I had passed out, knocking down the lamp on my way to the floor.
Back when I had an iron deficiency and fainted several times, it took me a couple faintings to realize that I could reliably be forewarned about incoming problems through a static-y fuzz that would start creeping in around the edge of my vision. I learned that through focusing on and staring down my hand I could fight this wave off and be OK.
This was different: I've had times before in bed where I might start to obsessively think about something or recollect some past event in extremely vivid clarity. Clearly something was wrong, but it was also an extremely interesting phenomenon and so I let my mind chase it. My mind was clearly tripping out, but I was in bed and thus safe so went with it to see what was happening and try to figure out why my brain might be getting delirious. When I started getting vertiginous I'd stop and go to sleep. Father's Day was the first day this kind of weirdness had happened in daily ordinary life: I hadn't associated it with fainting before, but that makes sense.
This morning I was driving to the company store and had a moment of panic wherein I couldn't figure out which side of the road I should be driving on. I'm not sure what was going on there and quickly managed to reassert reality... but still: odd.
So that's something to look out for now. I figure I'm probably physically OK, but I'll get myself checked out just in case.