4) Insidious

The combination of the typical jump scare tension, a sense of mystery and unexplainable paranormal activity as it unleashes on couple Josh and Renai, whose son unexplainably falls into a coma after they set up family life in a new home, makes the 2011 horror an unmissable watch.

Those who watched Patrick Wilson (pictured) try and save his son from a demon had an average heart rate of 85 beats per minute – with the highest spike reaching 133.