Fainting
at the sight of blood once had a purpose.
The mere sight of
blood can make some of us feel light-headed. I’m getting a little breathless
just writing this. For others, seeing blood can cause them to actually pass
out. While it’s not serious, it can certainly be frightening. We’ve seen the
trope in movies dozens of times — the man who claims to be a doctor only to
pass out when his love interest cuts her finger. But why does this happen?
Well, it all comes
down to vasovagal syncope. The vasovagal syncope trigger causes your heart rate
and blood pressure to drop suddenly. That leads to reduced blood flow to your
brain, causing you to briefly lose consciousness. It can be caused by the sight
of blood or sudden emotional distress.
Evolution
Why would blood cause
us sudden distress though? The answer may lie with our cavemen ancestors. It
may have been a survival technique. Fred Jaeger, DO,
medical director of the Center for Syncope and Autonomic Disorders at the
Cleveland Clinic in Ohio, spoke to NBC News on
the subject. “For example, if you’re a caveman and another caveman comes over
and cuts your arm off, the sight of blood or injury may cause you to faint, so
when you’re laying there on the ground, you’ll look like you’re dead to the
other caveman and he won’t cut your head off.” Fainting at the sight of
blood once had a purpose.
There may be a reason
why women of yore were prone to fainting or swooning too. The vasovagal syncope
is more common in
women, as women tend to have a higher resting heart rate and lower
blood pressure.
Look away
If you are the type
of person who feels faint at the sight of blood, you just need to look away. It
sounds obvious, but part of the sensation of vasovagal syncope can come from
feeling out of control in the situation.
In a 2015 study, participants
were divided into “perceived control” and “no perceived control” groups. They
were shown a video of mitral valve surgery, which is known to trigger vasovagal
syncope in non-medical personnel. The participants with no perceived control
reported significantly more vasovagal symptoms and anxiety, compared with those
who could take a break.
Signs to watch out
for
Not sure you’re the
type of person who faints at the sight of blood? We don’t recommend you prick
your finger and see what happens. Watch out for these symptoms instead:
·
Feeling
lightheaded or dizzy
·
Seeing
spots or stars in front of your eyes
·
Have
trouble breathing
·
Your
fingertips and lips start to tingle
·
You
feel hot suddenly
·
You
feel nauseous
·
Your
skin takes on a blueish tint
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