Bloodcurdling has been very controversial for the past years as the term was based on the concept that horror or fear could cold the blood or "curdle" it. So, to check if there's any truth behind the concept a group of Dutch researchers dug onto it.

A group of researchers from Leiden University in the Netherlands recruited 24 healthy individuals who are aged 30 and below, 14 of the participants watched the 2010 horror movie, Insidious. After a week, they watched a documentary scene A Year in Champagne. The rest of the participants did the same thing but in opposite order with the same week gap.

Fifteen minutes before and after filming, blood sample were taken from the movie participants. Researchers found out that there was a significant increased levels of factor VIII for those people who watched the horror movie. The reading has been linked with an increased risk of a "venous thrombosis," or "blood clot." While those who were assigned in the educational film decreased.

Dr Banne Nemeth said, "We found watching horror, or 'bloodcurdling', movies was associated with an increase in blood coagulant factor VIII." Further explaining, "The mean increase in factor VIII levels of 11.1 IU/dL associated with acute fear could be clinically relevant, as every 10 IU/dL increase in coagulant factor VIII levels is associated with a 17 per cent increase in the risk of venous thrombosis."

But although the tests suggested there was coagulation by acute fear, this however does not lead to actual clot formation. "The underlying biological mechanism of acute fear associated with an increase in coagulation activity is still to be unraveled," Dr Nemeth added.

The study now justified the "bloodcurdling" term after researchers concluded watching scary movie can "increase in blood coagulant factor VIII" but "without actual thrombin formation."

The research was titled Bloodcurdling Movies and Measures of Coagulation: Fear Factor Crossover Trial Dr Nemeth and Doctor Luuk Scheres were the specialists who conducted the research and their study was published in the Christmas edition of the British Medical Journal.