I'm alive, and I actually know what the issue is, more or less. Perhaps TMI (and better not in the game thread) but:

https://en.wikipedia.org/wiki/Vasovagal_response

Shortish version, your body has the "voluntary nervous system" which controls muscles like your biceps, and the autonomic nervous system which controls all the stuff that falls more or less under involuntary response - heartbeat, digestion, etc.

And the autonomic system has two general functions - ramping up ("sympathetic" adrenaline, etc.) and cooling down (parasympathetic). In certain conditions my brain just tells the arteries/veins in my lower body to dilate, and whoosh, all the blood goes down into that space. With insufficient blood in the heart to pump, the heart stops - the survival mechanism being that passing out brings all the blood level and it can flow back into the heart and to the brain.

When you pee you feel relaxed, right? That's parasympathetic. My brain just tells my system to relax too much sometimes in conjunction with certain secondary triggers.

Happened for the first time when I was 24 or so and I ended up in the hospital for 2-3 days. At the time some enterprising surgeon wanted to put me on a pacemaker, but I pointed out the real issue is the lack of blood in the heart. He really just wanted to do the surgery, I think, so he conceded but noted that, while my heart is young it can probably keep restarting on its own. Eventually, it won't. Or I'll fall and seriously hurt myself. Or get stuck collapsed in an upright position and seize over and over (that happened once the night I tore my ACL) because the heart/brain can't get enough blood back north to restart properly.

Before I had a child I never really worried about it. It freaks the shit out of my spouse. Haven't decided whether to tell her.

The combination of shock and urination is a double-whammy for me. Other people have slightly different triggers which the wiki goes into, but they all tend to involve some aspect of the parasympathetic system. The nyquil made me dizzy/nauseous (doesn't usually), and that was enough. What was scary last night was both how fast it happened, how hard that bleepin' floor is, and how I still couldn't sleep afterwards.

But at least in current medicine there's really nothing they can do for me, either as prevention or after the fact. If I'd gone in to the ER it would have been mostly for them to knock me out so I could sleep and perhaps give me stitches.

Pretty sure I didn't get a concussion - I've had them before from sports. Neck hurts, though, and have a pretty decent lump on my forehead - think that's where most of the blood came from. Think I chipped a tooth slightly. I think I'm going to rest a few more hours before trying to either go out to forage for food or make it to my conference.

Gonna have to give the maids a good tip, though.