There's some triggers I can control. I've fainted in the bathtub because of steam, so I'm careful not to have too much steam. I've fainted a few times while getting blood drawn, what works for me is when the person keeps talking to me and has my focus the whole time. I've fainted when there's too little oxygen in the room, so I just get out. I've fainted during flights, so I eat, drink, turn on the fan and point it to my head, make sure I'm not overheating if the sun hits me directly, go to the toilet, keep myself engaged. When I faint my eyes stay open, but my mind is just gone, last time I was out for one and a half minutes.
Nothing to be ashamed of. Your Vagus Nerve, the main signaling nerve for your autonomic system, can go off automatically and there’s nothing you can do to stop it. When it happens, sit down in a chair. If you can lean back and put your feet up, that’s better and the episode will resolve more quickly. These episodes will come and go quicker as you are prepared for them.
My wife has had to these for years. The only treatment we’ve found helpful is transcutaneous vagus nerve stimulation (tVNS) with a tool like a Neuvana Xen - or you can go the expensive prescription route. We were actually treating her gastroparesis with this and found that modulating the signal worked for all sorts of misfirings - like when getting shots.
TLDR: You can’t avoid them, but you can mitigate them by sitting in a chair, leaning back, and bringing your feet closer to your heart. If anyone is watching, it just looks like you are trying out the recline function of the chair. If your Vagus Nerve issues are bad, you can try tVNS (under the supervision of your doctor, of course).
Oddly, putting my feet closer to my heart (such as when washing my lower legs in the shower) seems to unplug my sinuses if they’re plugged. Related mechanism?
I’m guessing they meant when they lean over, but the movement should be what does it. This movement uses gravity and the pooling of blood to force the liquid out of their sinuses - probably only temporarily though. Does it work the same way if they were to lean over the bed? If so, that’s the answer.
There is a number of sinus decongesting massage moves that work well. These use pressure and blood flow to force the liquid out of your sinuses and then uses gravity to take it away. I use these to help relieve sinus pressure.
But, to answer the original question, this is only related tangentially. Laying down, picking up your feet, and breathing generates a signal in your Vagus Nerve complex that essentially overrides the fainting signal. It’s still there, but you’ve added a new stronger signal to dominate the nerve and the fainting signal starts to fade. Simple meditative breathing does the same, but usually not fast or strong enough to stop you from syncope.
> I’m guessing they meant when they lean over, but the movement should be what does it.
Oh, no; the motion I'm referring to doesn't involve moving my head at all. I meant that I raise my right knee while balancing on my left leg, to scrub my right calf by bringing it into reach. (Is this not how most people clean their legs in the shower?) Doing this — and holding the pose for at least a few seconds — almost always unplugs my right sinus. (And only the right sinus. Have to raise my left leg to unplug my left sinus!)