According to some scientists, watching horror movies might have some evolutionary benefit in the response to life-threatening situations.

A new study claims that the amount of a clotting protein, Factor VIII, increases in our blood when we become frightened. They speculate that an increase in clotting agents could help the body prepare for blood loss during life-threatening situations.

Researchers from Leiden University Medical Center in Netherlands took 24 healthy volunteers, all under 30. Out of them, 14 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. According to the findings, 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 viewers over the course of watching the educational movie.