1. Low blood pressure falling over
2. Just gave blood falling over
3. Vasovagal falling over
The first style is something I engage in quite often. I was blessed/cursed with obscenely low blood pressure: blessed because I probably won't ever suffer any of the numerous health problems associated with high blood pressure, but cursed because it makes me especially prone to falling over. This style of fall-over requires no special circumstances other than going from a sitting to standing position quickly.
My blood pressure is so very low that when I transition from sitting to standing, there isn't enough pressure to entirely overcome gravity. I quickly find that there isn't enough blood in my brain, and so... I often wobble or entirely fall over.
Since I have low blood pressure to begin with, giving blood can be treacherous. I've only donated blood 3 times.
The first time I gave blood when I was 17, things went swimmingly.
Because I have a rare blood type, B-, the blood bank called me again a few months later to ask that I donate again. I said, "For suresies. I could use some free cookies anyway." While I didn't fall over the second time I donated, I did feel a bit woozy afterwards. But nothing that sitting for a few minutes and having some apple juice didn't fix.
A few months later, I got another call from the blood bank asking for my precious life stuff. I didn't see any harm in going again.
When they called again a few months later, I politely declined.
Before we talk about what on earth vasovagal means, I need to give you some quick background on your autonomic nervous system. The autonomic nervous system is responsible for responding to external stimuli and adjusting your body accordingly without consulting you. Bright light? Narrow the pupils. We're running? Increase the heart rate! These things aren't left up to your whims. They happen automatically (unless something is wrong with you).
The autonomic nervous system is a coin with two sides: the sympathetic side, and the parasympathetic side.
The sympathetic division is responsible for the so-called "fight or flight" reaction. As the nickname suggests, this side is a response to some serious stress. When the sympathetic division is in gear, your pupils dilate, your sweat glands work overtime, your heart rate increases, and digestion stops. No use wasting energy digesting your burrito when you're being chased by a grizzly bear.
The parasympathetic division is responsible for the "rest and digest" side of things. The pupils constrict, heart rate slows down, digestion resumes. This is the hippie mellow side of your nervous system.
These two sides or your autonomic nervous system can sometimes lead to something called a vasovagal reaction. After a period of stress, when your parasympathetic (rest/digest) division kicks in to calm things down, it can overcompensate for the stress and lower your heart rate too much, and you can pass out as a result. Vasovagal reactions are to blame for people passing out at the sight of blood.
This happened to me earlier this year when I got a shot. This particular shot (it's the HPV shot, if you really want to know) is more painful than normal immunizations because it's been refrigerated.
As you can see, my arm was very upset about this whole ordeal. It hurt like... well, you know. It hurt! The nurse gave me a bandaid (and not even a spongebob bandaid--just a plain one) and sent me on my way. While I walked out of the office, I put on my sweater, which unfortunately involved moving my shoulder near the injection site. This was bad.
It was then that my autonomic nervous system said, "Okay, our turn to deal with this."
I felt my heart beating wildly.
Then I felt dizzy.
Then I couldn't hear anything other than a high pitched ringing.
Then I started getting tunnel vision and eventually couldn't see anything.
At the same time, my legs stopped working.
Luckily this happened next to a chair, so I took advantage of its wonderful sitting-on properties, and slumped into it.
I sat there for maybe 5 minutes waiting for luxuries like seeing and hearing to return to me. Then I drove home.
And those are the 3 ways I occasionally almost die. The end!