Fear Can Actually Curdle Your Blood

Illustration for article titled Fear Can Actually Curdle Your Blood

The next time someone refers to a horror movie as “bloodcurdling,” they might actually be kinda right. A new study shows that the fear experienced when watching scary movies is in fact associated with an increase in clotting agents in the blood.


A team of researchers from the Leiden University Medical Center in the Netherlands has published its findings in the Christmas issue of the British Medical Journal—which famously prints light-hearted studies to read during the holidays.

The team took 24 healthy volunteers, all under 30. Fourteen of them watched a horror movie, then an educational movie a week later; the other ten watched the educational movie, followed by the horror movie the following week. Blood samples were taken before and after each viewing.


The results show that the levels of the coagulant factor VIII in the blood increased in the majority of viewers during the horror movie, and decreased in the majority of views over the course of the educational movie. No other clotting agents seemed to be affected. In other words, the blood was in some sense primed to clot in the presence of fear.

It’s obviously supposed to be a fun experiment, but the researchers point out that there may be some evolutionary benefit in the response. They speculate that an increase in clotting agents could help the body prepare for blood loss during life-threatening situations. Though hopefully that won’t be required during your next horror movie viewing.

[BMJ via Medical Express]

Image by iaodesign/Shutterstock


Share This Story

Get our newsletter



This isn’t surprising. The fear response includes a big squirt of epinephrine which increases your heart rate and constricts blood vessels so you can run from the bear faster and bleed less when it bites. That your body also dumps clotting factors dovetails with this system nicely. What’s really surprising is that this hadn’t been recognized previously.