In fact, according to the Stress Management Center and Phobia Institute in Asheville, North Carolina, an estimated 17 to 21 million people in the United States are affected by a fear of this day. Some are so affected by their fear that they avoid normal routines and refuse to conduct business on Friday the 13th.
So how did Friday the 13th become such an unlucky day? Several theories are advanced for why Friday the 13th is considered so unlucky by so many. In numerology, for example, the number 12 is considered a good luck number -- there are 12 months of the year, 12 hours on a clock, 12 signs of the zodiac, Jesus had 12 apostles, 12 tribes of Israel, and so on.
By contrast, the number 13 has traditionally been considered unlucky. One superstition, thought to derive either from the Last Supper or Norse mythology, suggests that having 13 guests for dinner will result in the death of one of the diners.
At the Last Supper, Jesus and his 12 apostles gathered to dine, making 13 total. It was Judas, the apostle who betrayed Jesus, who was the the 13th guest to arrive that night.
Whatever its origins, the belief in the bad luck qualities of the number 13 is so enduring that most high-rise buildings do not have a 13th floor.
Christian tradition has also regarded Friday as an unlucky day. According to Biblical scripture, for example, Jesus was crucified on a Friday. Some historians suggest the Christian distrust of Fridays is actually linked to the early Catholic Church's suppression of pagan religions and women. In the Roman calendar, Friday was devoted to Venus, the goddess of love. When Norsemen adapted the calendar, they named the day after Frigg, or Freya, Norse goddesses connected to love and sex. Both of these strong female figures once posed a threat to male-dominated Christianity, the theory goes, so the Christian church vilified the day named after them.
This theory was popularized in the 2003 novel The Da Vinci Code.