Do you ever stand up too fast and get lightheaded?  It’s a momentary sensation, but it makes the entire room look like a funhouse mirror.  You know what I’m talking about.  When it happens, you might notice the color of the room changing, or little blurbs of light zipping across your vision (seeing stars).  As a kid, I remember my friend’s mom telling me those little blurbs of light were angles.  From what I understand now, my friend’s mom is a liar. 

What’s actually going on here is your pathetic meat-body is losing a little blood pressure to the brain.  It’s nothing serious, generally.  You stand up too fast, the blood that was in your head rushes down toward your legs, you feel like you’re going to pass out, then you take a few breaths, and you’re fine.  This is usually the case, unless you already suffer from abnormally low blood pressure – then you might actually pass the fuck out.

The next time you go to the doctors, watch the old people when they stand up.  It’s way more entertaining than whatever shitty newscast they have playing on the waiting room televisions.  The nurse will come out with her clipboard, “Alondra Gutierrez…Alondra Gutierrez…”  And you’ll see old, overweight Alondra Gutierrez cap her diet coke and stand up in a hurry.  It will be obvious in her first step or two.  Depending on how many decades have gone by since she last jogged, she might even have to brace momentarily on the edge of the chair.  Then she’ll gain her composure, wobble her way over to the nurse, and you’ll be left to watch shocking new footage of someone being tear gassed by police. 

Now imagine that lightheaded feeling times about a thousand.  That’s what G-LOC is.  G-LOC is a gravitational force induced Loss of Consciousness.  It mainly affects fighter pilots and astronauts when they experience excessive and sustained g-forces, so it’s a little different than your dizzy spell.  During G-LOC, the high gravitational forces force blood away from the head and into the lower extremities.  If that continues for long enough, it can quickly result in loss of consciousness – especially in untrained people.

We’re not talking about taking that 25 mile per hour off ramp at 40 in your mom’s Mazda.  We’re talking about fighter jets that can pull up to 9 Gs.  That’s like having 9 of you sitting on your own chest.  Of course pilots and astronauts undergo rigorous training to manage and prepare for these high gravitational forces.  While you, on the other hand, continue to get lightheaded every time the doorbell rings.

When blood begins moving away from the brain toward the feet, there are a few indicators.  The first is a Greyout, where you lose the color in your vision.  Unless you’re a Labrador, this is where you should probably start worrying.  The next level of “I’m about to pass the fuck out,” is Tunnel Vision.  During tunnel vision, you lose some or all of your peripheral vision.  The Blackout is third.  Blackouts occur when you have a complete loss of vision without loss of consciousness.  This type of Blackout is not to be confused with the empty space in your drunken memory where you did or didn’t do that thing with what’s her name (you probably did).

Lastly we have G-LOC, or sleeping on the job.  When pilots experience G-LOC, they go completely unconscious. The time out on a typical G-LOC is 12 seconds, but it takes about 25 seconds to regain your bearings – plenty of time to crash and die.

These changes leading up to G-LOC, and even your lightheadedness upon standing, are caused by the sensitivity of your eye’s retina.  Eyeballs are sensitive to hypoxia, or deprivation of adequate oxygen, which allows even subtle changes in pressure to effect the vision.  A well trained pilot can actually use these indicators to gauge how many more Gs his body can handle. 

If you watched Top Gun recently, you’re probably asking yourself, why didn’t Tom Cruise experience G-LOC?   I can explain.  Tom Cruise is a Scientologist – the rules of gravity don’t apply.  But typically, outside of the utopia of scientology, an untrained human will lose consciousness between 4-6Gs.  A trained pilot or astronaut, on the other hand, can handle upwards of 9Gs.

Handling high Gs isn’t easy.  On top of wearing special G-suits, pilots practice a special straining maneuver where they tense the muscles in their legs and arms and expel air in short bursts.  This helps to stop blood from pooling in the lower extremities and can be essential for keeping a pilot conscious.

Here’s a video of a pilot in a training centrifuge, successfully preventing G-LOC.  This is how stupid non Scientologist have to look to stay conscious.