Scary movies can curdle blood

Maybe the body is preparing for possible injury?

Public Release: 16-Dec-2015
Scary movies can curdle blood
BMJ (British Medical Journal)

Watching horror, or 'bloodcurdling,' movies is associated with an increase in the clotting protein, blood coagulant factor VIII, finds a small study in The BMJ Christmas issue this week.

The results suggest that using the term 'bloodcurdling' to describe feeling extreme fear is justified, say the researchers.

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The difference in coagulant factor VIII levels before and after watching the movies was higher for the horror movie than for the educational movie.

Levels increased in 12 (57%) participants during the horror movie, but only in 3 (14%) during the educational movie. Levels decreased in 18 (86%) participants during the educational movie, but only in 9 (43%) during the horror movie.

However, the researchers found no effect of either movie on levels of other clot-forming proteins, suggesting that although coagulation is triggered by acute fear, this does not lead to actual clot formation.

They point out some study limitations, but conclude that, in young and healthy adults, "watching bloodcurdling movies is associated with an increase in blood coagulant factor VIII without actual thrombin formation."