At this time of year we flock to horror films and prepare ghoulish costumes - but why do we do this? For children the answer is easy: sweet treats. For adults, the attraction to frightening things is a bit more complicated. One in six people in Great Britain experience anxiety or depression each week. Though many struggle with inner demons, they are also attracted to the macabre and the terrifying. It seems like a paradox but Dr Peter Kinderman says taking part in Halloween traditions can be therapeutic.