Horror films actually make the blood 'curdle', scientists find

A protein associated with blood clotting rose when participants in the study watched a horror film

Films like 'Halloween: Resurrection' can curdle the blood' according to researchers (Snap Stills/REX Shutterstock)

The saying goes that horror films are blood curdling – now scientists believe they have proven that the idea is true.

A team of Dutch scientists set out to discover whether being afraid can curdle the blood – an adage used since the medieval times.

As part of a study published in the Christmas issue of the British Medical Journal, researchers assessed the reactions of 24 healthy young adults as they were show the 2010 horror film Insidious as well as the educational film called A Year in Champagne.

They found that the levels of protein rose significantly after watching the scary film.

On average, there was a 11 IU/dl (International Unit/decilitre) increase of the protein factor VIII in their blood, which helps the liquid to clot.

Such a rise is associated with a 17 per cent rise in the risk of venous thrombosis.

However, the evidence did not show that watching horror films could make a person’s blood clot.

Dr Banne Nemeth, who lead the study, told The Telegraph: “The underlying biological mechanism of acute fear associated with an increase in coagulation activity is still to be unravelled,” the team’s leader,

"Although it’s not immediately obvious by which means our results could confer clinical benefits, a broader implication of these study results is that after centuries the term ‘bloodcurdling’ in literature is justified."