JUN 08, 2016 6:14 AM PDT

Why does the sight of blood make some people faint?


Have you ever wondered why some people faint at the sight of blood? A fear of blood is classified as a phobia, which is an intense irrational fear of something that causes your body to react by going into fight or flight mode, and approximately 3-4% of people have a blood, injury, or injection phobia. But unlike other phobias, phobias of blood, injury, and injection can actually cause a person's blood pressure and heart rate to go up and then suddenly drop, which can cause them to lose consciousness among, other symptoms.

A nerve called the vagus nerve causes a drop in blood pressure when it is triggered by certain external stimuli like pain, dehydration, or sudden fear, among other causes. Scientists think that this nervous system reaction may be an evolutionary trait that lowers blood pressure at the sight of blood to prevent bleeding to death.

Researchers have found an effective way to cure certain phobias. The phobic person must tense his or her muscles and then slowly be exposed to whatever they are afraid of little by little. Tensing up stops the drop in blood pressure from happening. In the case of a blood phobia, they show the phobic person a spot of red, and then a larger spot of red, then a picture of blood, and finally blood.

Source: Geobeats
About the Author
  • Kathryn is a curious world-traveller interested in the intersection between nature, culture, history, and people. She has worked for environmental education non-profits and is a Spanish/English interpreter.
You May Also Like
JUL 07, 2020
Neuroscience
How Blindsight Helps Us Explain Consciousness
JUL 07, 2020
How Blindsight Helps Us Explain Consciousness
Blindsight is the phenomenon in which blind people can interact with their environments even though they can't see i ...
AUG 20, 2020
Health & Medicine
Studying the World's Deadliest Animal
AUG 20, 2020
Studying the World's Deadliest Animal
Imagine hundreds of mosquitoes feeding on your arm for the sake of research! This is one unique aspect fueling the work ...
SEP 08, 2020
Space & Astronomy
Reusable Chinese Space Craft Lands Returns Earth
SEP 08, 2020
Reusable Chinese Space Craft Lands Returns Earth
The Chinese government has announced the safe return of a reusable spacecraft, called Chongfu Shiyong Shiyan Hangtian Qi ...
SEP 10, 2020
Space & Astronomy
Could There Be Life on Venus?
SEP 10, 2020
Could There Be Life on Venus?
Venus is the hottest planet in our solar system, reaching 465 degrees Celcius- a temperature hot enough to melt lead. Wh ...
SEP 24, 2020
Health & Medicine
Extreme Isolation can Cause Physical Brain Changes
SEP 24, 2020
Extreme Isolation can Cause Physical Brain Changes
By this point in the year, you’ve either heard or uttered the phrase “quarantine brain.” While the act ...
NOV 06, 2020
Chemistry & Physics
The Most Powerful X-ray Source On Earth
NOV 06, 2020
The Most Powerful X-ray Source On Earth
Located inside the Sandia National Laboratories in Albuquerque, New Mexico, the Z Pulsed Power Facility (or Z Machine) i ...
Loading Comments...