It looks they selected from a very limited list (no Asian movies?) and only measure heartrate.
A follow up study of movies most likely to cause nightmarish moods for a week would be interesting. On a scale of 1 to 10...how lifechanging was Threads? :p
Topical list, I don’t agree with the science.
https://screencraft.org/blog/these-are-the-scariest-movies-according-to-science/