Years in, years out, people all over the world have considered the number thirteen to be so unlucky. Some hotels don’t have a thirteenth floor, whilst some airlines miss the thirteenth row in their planes. Some people even place a teddy bear at the dining table to make sure that there are fourteen 'people' at a dining table and not thirteen. But why do people have triskaidekaphobia (irrational fear of 13)?

Christians believe that 13th person who joined Jesus for his Last Supper was none other than Judas, the one who betrayed Jesus.

In Norse Mythology, a dinner party at Valhalla was interrupted by the 13th Norse God, Loki, who was uninvited, caused chaos at the party and resulted in a god’s death, making it a very mournful day.

Twelve is also considered to be a perfect number. There are 12 hours on a clock, 12 months in a year, 12 zodiac sign… the fact that the number thirteen follows twelve, makes people fear the unknown.  

Published in the British Medical Journal in 1993, “Friday 13th is unlucky for some. The risk of hospital admission as a result of a transport accident may be increased by as much as 52%. Staying at home is recommended” grew media attention and scared many people. This by, no means, is confirmed and actually, a recent study conducted by CE Safety found it to be more likely to die at work on a Tuesday the 8th. 

However, this fear of Friday the 13th is so intense that a) it has a name 'paraskevidekatriaphobia' and b) the Stress Management Center and Phobia Institute in North Carolina estimates between $700 million and $800 million are lost every Friday the 13th, because some people refuse to get out of their bed, let alone do business. 

This year, the occurrence of both Friday and 13th together will be in August.