In a 2012 study, funded by the former video subscription service Lovefilm, researchers from the University of Westminster in the UK asked 10 people to watch 10 different scary movies as they monitored heart rate, oxygen intake and output of carbon dioxide. The 1980's film The Shining, starring Jack Nicholson, topped the list of the calorie-scorching horror films. The person who viewed it jumped and shrieked themselves rid of 184 calories: roughly the number of calories a 140-pound adult would burn after 40 minutes of walking, according to the American Council on Exercise's physical activity calorie counter. Jaws and The Exorcist took the second and third spots on the list, burning 161 and 158 calories, respectively.

The study was very small, and the findings were not published in a peer-reviewed journal. But there is other research that frightening flicks may proffer benefits. A 2003 study from Coventry University in the UK, published in the journal Stress, found that watching a horror film significantly increased people's circulating levels of disease- and infection-fighting white blood cells. Again, the study team credits the movie's ability to fire up the viewer's fight-or-flight response, which includes a short-term increase in immune function.

It might be simpler to think of horror movies as a form of "good stress." While stress gets a bad rap-and long-term stress is associated with everything from depression to heart attacks-brief bouts of stress have often been linked to improved immune function, says Firdaus Dhabhar.