Slide 1: When a “bloodcurdling” scream is heard, how may the coagulation cascade be affected?

Slide 2: Factor VIII levels increase!

Slide 3: In one crossover study, healthy participants were asked to watch a horror movie and an educational documentary. Coagulation factors were measured before and after, with significant increase in factor VIII levels after the scary movie only. Of note, no clinical venous thromboembolic events occurred. Graphic showing the pathway for fibrin clot formation.

Slide 4: This lends some credence to the age-old usage of the term “bloodcurdling” to describe a frightening situation. Similar effects have been noted to occur in other thrilling situations, such as bungee jumping. Evolutionarily, the rise in factor VIII levels is hypothesized to help prepare someone from bleeding out in the case of a dangerous predator.


  • Nemeth B, Scheres LJ, Lijfering WM, Rosendaal FR. Bloodcurdling movies and measures of coagulation: Fear Factor crossover trial. BMJ. 2015;351:h6367. Published 2015 Dec 16. PMID 26673787.
  • van Westerloo DJ, Choi G, Löwenberg EC, et al. Acute stress elicited by bungee jumping suppresses human innate immunity. Mol Med. 2011;17(3-4):180-188. PMID 21203694.

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