Friday the 13th
A fear of Friday the 13th is known as "friggatriskaidekaphobia."

With the weekend in sight, you'd think we'd all have that Friday feeling, but one third of Britons will be frantically changing their plans tomorrow.

It's Friday the 13th, a date synonymous with bad luck and misfortune.

With 72% of people claiming to have experienced bad luck on this date, up to a third of adults are so fearful of it, that they will readily admit to changing travel plans, rescheduling important meetings and if possible, will stay at home, well out of harm's way, resurfacing on the altogether less threatening Saturday the 14th.

A fear of Friday 13th is a recognised phobia, known as "friggatriskaidekaphobia." To make matters worse, 60% of Britons also suffer from "triskaidekaphobia" - the fear of the number 13, believing that it is the harbinger of bad luck.

In a study by hotel chain Travel Lodge, over half of Britain's adult population believe in the power of numbers to bring good and bad luck, a fact that plays a role in hospitals skipping the 13th floor and airports omitting gate 13, while hotel rooms with the number 13 on the door are very likely to remain unoccupied.

Shakila Ahmed, a spokesperson for Travelodge said: "It's evident that Triskaidekaphobia is hitting Britain hard. Britons really do have a fear of the number 13 and will avoid this number at all cost. At present just half of our hotels have a room 13 and we are now looking to see if we can rename these rooms."

It's not clear when or why Friday the 13th became associated with bad luck. It may have a bibilcal origin: the 13th guest at the Last Supper betrayed Jesus. His crucifixion was the next day, on a Friday.

With 12 months of the year, the 12 days of Christmas 12 signs of the zodiac, and 12 apostles, 13 perhaps suffers for being the odd number to follow the more equanimous 12.

The fear of Friday the 13th is something that the horror industry has picked up on, fuelling people's fears with slasher films such as Friday the 13th, and monopolising audiences on the inauspicious day.

According to Thomas Gilovich, chair of the department of psychology at Cornell University, the superstition around the date is the result of our brains ability to make strong associations.

"If anything bad happens to you on Friday the 13th, the two will be forever associated in your mind, and all those uneventful days in which the 13th fell on a Friday will be ignored," said Gilovich.

The Stress Management Centre and Phobia Institute in Asheville, N.C., reports that $900 million are lost on Friday the 13th, due to people's fear of flying or doing business as usual, with stockbrokers traditonally halting all investments on the day.

If a fear of Friday the 13th has you hiding under your duvet, you're in august company. Former US President Franklin D. Roosevelt is said to have avoided travel on the 13th day of any month, and would never host 13 guests at a meal.

Napoleon and President Herbert Hoover were also triskaidekaphobic, with an abnormal fear of the number 13. And the French are said to be so superstitious that, diners in Paris can hire a "quatorzieme," or a professional 14th guest to join them for dinner.

Gilovich stresses, however that there is no evidence linking Friday the 13th to bad luck or misfortune. "People hold a number of beliefs without understanding the basis behind them or where they came from," he explained.

That said, there have been some unusual happenings in history that occurred on Friday the 13th:

Nov. 13, 1789 - Benjamin Franklin wrote the immortal line: "Everything appears to promise that it will last; but in this world nothing is certain but death and taxes."

Sept. 13, 1940 - Five German bombs hit Buckingham Palace and destroyed the Palace Chapel, as part of Hitler's strategic "Blitz" bombing campaign.

June 13, 1952 - A Swedish military DC-3 plane carrying a crew of eight disappeared over international water in the Baltic Sea. This became known as the "Catalina affair" because one of two Catalina rescue planes sent to search for the plane was attacked by Soviet forces.

Nov. 13, 1970 - A huge South Asian storm killed an estimated 300,000 people in Chittagong, Bangladesh, resulting in floods that killed as many as 1 million in the Ganges delta.

June 13, 1986 - The Olsen twins, Mary-Kate and Ashley, were born.

Jan. 13, 1989 - The "Friday the 13th virus" infected hundreds of IBM computers across Great Britain, wiping out program files and causing considerable anxiety at a time when large-scale computer viruses were a relatively new threat.

Oct. 13, 1989 - The Dow Jones Industrial Average underwent the second largest drop it had ever experienced at that time. Nicknamed the "Friday-the-13th mini-crash," the Dow dropped 190.58 points that day.

Aug. 13, 1999 - This would have been the 100th birthday of Alfred Hitchcock, director of psychological thrillers such as The Birds and Psycho.

Sept. 13, 2013 - This was the planned date of the thirteenth instalment of the Friday the 13th horror film series.