A new study just released and cited on business-standard.com says the “bloodcurdling” feeling you get when watching a scary movie, or really in any frightening situation, is real, and and can lead to an increase in a blood clotting protein in the body.

The study, involving healthy volunteers who were under the age of 30 and were students, alumni or employees of the Leiden University Medical Center in the Netherlands, set out to investigate whether fear could actually curdle blood.  The researchers say blood curdling is an important evolutionary benefit that prepares the body to deal with the loss of blood in threatening situation where the body may become harmed.

The subjects were divided into two groups of 14 and 10 people, with the 14 asked to watch a scary movie and then an educational non-threatening movie.  The group of 10 was asked to watch the same movies in reverse order.

The movies lasted about 90 minutes each, and were viewed more than a week apart at the same time of day in a relaxed and comfortable environment.  Before and after each movie, samples of the subjects blood were taken and analyzed.

The participants also completed a questionnaire to determine if they had previously seen the movies, along with questions about their general lifestyle and favorite types of movies.

The findings show that the presence of a blood clotting protein, known as Factor VIII, increased in 12 of the 24 subjects during the horror movie, as compared to only three of 24 of those watching the educational movie.

The levels of the protein decreased in 18 of the 24 participants while viewing the educational movie, but only in nine of the viewers of the horror movie.

The good news is the researchers say they found no effect on any other clot-forming proteins during the study, and that suggests, while blood coagulation is a part of being scared, it does not appear to lead to the formation of an actual blood clot.

Watching a horror movie may make you feel like you are going to be scared to death, but this new research shows a blood clot is not likely to be the cause.

Findings of the study were published in The BMJ.