Friday the 13th fears explained

Today is Friday the 13th. For most, it is just another work or school day. Paraskevidekatriaphobes (people with a fear of Friday the 13th) are expecting a bad day though.

Months that begin on a Sunday will have a Friday the 13th. Each year has at least one. 2012 has brought us three, in January, April and July. If that's not bad enough for triskaidekaphobes (people with a fear of the number 13), those dates fall exactly 13 weeks apart.

According to Dr. Donald Dossey, an Asheville psychotherapist who coined the name for the phobia, about 7 percent of Americans fear Friday the 13th. This makes it among the most widespread western superstitions. Dossey estimates $800 million to $900 million in lost in business from people who refuse to fly or do business because they think the day is unlucky.

The number 13 has been seen as unlucky for centuries. The dark cloud over Fridays has long existed as well. Chaucer's "The Canterbury Tales" associated Friday with bad luck in the 14th century. It was natural to put the two together and further amplify the fear.

There is nothing special about the date on the calendar. As Dr. Neil deGrasse Tyson, astrophysicist, author and director of the Hayden Planetarium in New York City points out, "Thursday the 12th" is just as common as "Friday the 13th." 

A 1993 study published in the prestigious British Medical Journal concluded, "The risk of hospital admission as a result of a transport accident may be increased by as much as 52 percent. Staying at home is recommended." The study reviewed three to five years of records on traffic (at least 1.4 percent fewer vehicles on the road) and hospital admissions. However, that same study noted that Friday the 13th supermarket sales increase by .93 percent over previous Fridays.

The news isn't all bad however. Fridays are viewed very differently by Norse mythology where the day is sacred to Freya, the goddess of love and beauty.